Merge branch 'feat/ldgen_fast_reflashing' into 'master'

feat(ldgen): initial support for fast reflashing

Closes IDF-14213

See merge request espressif/esp-idf!42780

CMakeLists.txt

@@ -159,6 +159,10 @@ if(CONFIG_COMPILER_NO_MERGE_CONSTANTS)
     list(APPEND compile_options "-fno-merge-constants")
 endif()
 
+if(CONFIG_COMPILER_ENABLE_TEXT_SECTION_LITERALS)
+    list(APPEND compile_options "-mtext-section-literals")
+endif()
+
 if(CONFIG_COMPILER_STACK_CHECK_MODE_NORM)
     list(APPEND compile_options "-fstack-protector")
 elseif(CONFIG_COMPILER_STACK_CHECK_MODE_STRONG)

Kconfig

@@ -576,6 +576,20 @@ mainmenu "Espressif IoT Development Framework Configuration"
                 distribution is more uniform across libraries. On downside, it may increase
                 the binary size and hence should be used during development phase only.
 
+        config COMPILER_ENABLE_TEXT_SECTION_LITERALS
+            bool
+            depends on IDF_TOOLCHAIN_GCC
+            depends on IDF_TARGET_ARCH_XTENSA
+            default y if ESPTOOLPY_FAST_REFLASHING
+            help
+                Intersperse Xtensa literals within the text section to keep
+                them as close as possible to their references. This prevents
+                literals from being placed into a separate section in the
+                output file and prevents the linker from combining literal
+                pools from different object files. Enabling this is necessary
+                for fast reflashing to prevent mixing code from mutable and
+                immutable libraries.
+
         config COMPILER_WARN_WRITE_STRINGS
             bool "Enable -Wwrite-strings warning flag"
             default "n"
@@ -784,3 +798,4 @@ mainmenu "Espressif IoT Development Framework Configuration"
             - CONFIG_GDMA_ENABLE_WEIGHTED_ARBITRATION
             - CONFIG_I3C_MASTER_ENABLED
             - CONFIG_MBEDTLS_ESP_IDF_USE_PSA_CRYPTO
+            - CONFIG_ESPTOOLPY_FAST_REFLASHING

components/esp_system/ld/esp32/sections.ld.in

@@ -21,6 +21,10 @@ SECTIONS
 
     mapping[rtc_text]
 
+    /* mutable libs begin */
+    mutable[rtc_text]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.literal .text .literal.* .text.*)
 
     _rtc_text_end = ABSOLUTE(.);
@@ -51,6 +55,10 @@ SECTIONS
 
     mapping[rtc_force_fast]
 
+    /* mutable libs begin */
+    mutable[rtc_force_fast]
+    /* mutable libs end */
+
     *(.rtc.force_fast .rtc.force_fast.*)
 
     ALIGNED_SYMBOL(4, _rtc_force_fast_end)
@@ -70,6 +78,10 @@ SECTIONS
 
     mapping[rtc_data]
 
+    /* mutable libs begin */
+    mutable[rtc_data]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.*)
 
     _rtc_data_end = ABSOLUTE(.);
@@ -85,6 +97,10 @@ SECTIONS
 
     mapping[rtc_bss]
 
+    /* mutable libs begin */
+    mutable[rtc_bss]
+    /* mutable libs end */
+
     _rtc_bss_end = ABSOLUTE(.);
   } > rtc_data_location
 
@@ -224,6 +240,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > iram0_0_seg
 
   .dram0.data :
@@ -239,6 +260,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > dram0_0_seg
 
@@ -277,6 +303,10 @@ SECTIONS
 
     mapping[extern_ram]
 
+    /* mutable libs begin */
+    mutable[extern_ram]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(4, _ext_ram_bss_end)
   } > extern_ram_seg
 
@@ -289,8 +319,13 @@ SECTIONS
      * ldgen places all bss-related data to mapping[dram0_bss]
      * (See components/esp_system/app.lf).
      */
+
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > dram0_0_seg
 
@@ -377,6 +412,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
 
     /* Literals are also RO data. */
@@ -411,6 +451,10 @@ SECTIONS
     _rodata_reserved_end = ABSOLUTE(.);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   .flash.text :
@@ -425,6 +469,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.warning)
     *(.gnu.linkonce.literal.* .gnu.linkonce.t.*.literal .gnu.linkonce.t.*)
@@ -466,6 +515,10 @@ SECTIONS
 
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     _iram_data_end = ABSOLUTE(.);
   } > iram0_0_seg
 
@@ -475,6 +528,10 @@ SECTIONS
 
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
     ALIGNED_SYMBOL(4, _iram_end)
   } > iram0_0_seg

components/esp_system/ld/esp32c2/sections.ld.in

@@ -24,6 +24,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > iram0_0_seg
 
   /**
@@ -42,7 +47,12 @@ SECTIONS
  .dram0.bt.data :
   {
     _data_start = ABSOLUTE(.);
+
     mapping[dram0_bt_data]
+
+    /* mutable libs begin */
+    mutable[dram0_bt_data]
+    /* mutable libs end */
   } > dram0_0_seg
 
   .dram0.bt.bss (NOLOAD) :
@@ -51,6 +61,10 @@ SECTIONS
 
     mapping[dram0_bt_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bt_bss]
+    /* mutable libs end */
+
     _bss_bt_end = ABSOLUTE(.);
   } > dram0_0_seg
 
@@ -67,6 +81,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > dram0_0_seg
 
@@ -94,8 +113,13 @@ SECTIONS
      * ldgen places all bss-related data to mapping[dram0_bss]
      * (See components/esp_system/app.lf).
      */
+
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > dram0_0_seg
 
@@ -114,6 +138,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.linkonce.t.*)
     *(.gnu.warning)
@@ -216,6 +245,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
     . = ALIGN(ALIGNOF(SECTION_AFTER_FLASH_RODATA));
   } > default_rodata_seg
@@ -287,6 +321,10 @@ SECTIONS
     _rodata_reserved_end = ADDR(.flash.tbss);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   /* Marks the end of IRAM code segment */
@@ -301,6 +339,10 @@ SECTIONS
 
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     _iram_data_end = ABSOLUTE(.);
   } > iram0_0_seg
 
@@ -310,6 +352,10 @@ SECTIONS
 
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
   } > iram0_0_seg
 
@@ -324,6 +370,10 @@ SECTIONS
 
     mapping[iram0_bt_text]
 
+    /* mutable libs begin */
+    mutable[iram0_bt_text]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(16, _iram_end)
   } > iram0_0_seg
 

components/esp_system/ld/esp32c3/sections.ld.in

@@ -23,6 +23,10 @@ SECTIONS
 
     mapping[rtc_text]
 
+    /* mutable libs begin */
+    mutable[rtc_text]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.text .text.*)
     *(.rtc_text_end_test)
 
@@ -46,6 +50,10 @@ SECTIONS
 
     mapping[rtc_force_fast]
 
+    /* mutable libs begin */
+    mutable[rtc_force_fast]
+    /* mutable libs end */
+
     *(.rtc.force_fast .rtc.force_fast.*)
 
     ALIGNED_SYMBOL(4, _rtc_force_fast_end)
@@ -63,6 +71,10 @@ SECTIONS
 
     mapping[rtc_data]
 
+    /* mutable libs begin */
+    mutable[rtc_data]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.* .srodata.*)
 
     _rtc_data_end = ABSOLUTE(.);
@@ -78,6 +90,10 @@ SECTIONS
 
     mapping[rtc_bss]
 
+    /* mutable libs begin */
+    mutable[rtc_bss]
+    /* mutable libs end */
+
     _rtc_bss_end = ABSOLUTE(.);
   } > rtc_data_location
 
@@ -164,6 +180,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > iram0_0_seg
 
   /**
@@ -189,6 +210,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > dram0_0_seg
 
@@ -216,8 +242,13 @@ SECTIONS
      * ldgen places all bss-related data to mapping[dram0_bss]
      * (See components/esp_system/app.lf).
      */
+
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > dram0_0_seg
 
@@ -236,6 +267,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.linkonce.t.*)
     *(.gnu.warning)
@@ -338,6 +374,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
     . = ALIGN(ALIGNOF(SECTION_AFTER_FLASH_RODATA));
   } > default_rodata_seg
@@ -409,6 +450,10 @@ SECTIONS
     _rodata_reserved_end = ADDR(.flash.tbss);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   /* Marks the end of IRAM code segment */
@@ -430,6 +475,10 @@ SECTIONS
 
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     _iram_data_end = ABSOLUTE(.);
   } > iram0_0_seg
 
@@ -439,6 +488,10 @@ SECTIONS
 
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
     ALIGNED_SYMBOL(16, _iram_end)
   } > iram0_0_seg

components/esp_system/ld/esp32c5/sections.ld.in

@@ -28,6 +28,10 @@ SECTIONS
 
     mapping[rtc_text]
 
+    /* mutable libs begin */
+    mutable[rtc_text]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.text .text.*)
     *(.rtc_text_end_test)
 
@@ -48,6 +52,10 @@ SECTIONS
 
     mapping[rtc_force_fast]
 
+    /* mutable libs begin */
+    mutable[rtc_force_fast]
+    /* mutable libs end */
+
     *(.rtc.force_fast .rtc.force_fast.*)
 
     ALIGNED_SYMBOL(4, _rtc_force_fast_end)
@@ -65,6 +73,10 @@ SECTIONS
 
     mapping[rtc_data]
 
+    /* mutable libs begin */
+    mutable[rtc_data]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.* .srodata.*)
 
     _rtc_data_end = ABSOLUTE(.);
@@ -80,6 +92,10 @@ SECTIONS
 
     mapping[rtc_bss]
 
+    /* mutable libs begin */
+    mutable[rtc_bss]
+    /* mutable libs end */
+
     _rtc_bss_end = ABSOLUTE(.);
   } > lp_ram_seg
 
@@ -179,6 +195,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > sram_seg
 
   /* Marks the end of IRAM code segment */
@@ -196,6 +217,10 @@ SECTIONS
 
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     _iram_data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -205,6 +230,10 @@ SECTIONS
 
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
     ALIGNED_SYMBOL(16, _iram_end)
   } > sram_seg
@@ -232,6 +261,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -261,6 +295,10 @@ SECTIONS
      */
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > sram_seg
 
@@ -278,6 +316,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.linkonce.t.*)
     *(.gnu.warning)
@@ -387,6 +430,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
     . = ALIGN(ALIGNOF(SECTION_AFTER_FLASH_RODATA));
   } > default_rodata_seg
@@ -466,6 +514,10 @@ SECTIONS
     _rodata_reserved_end = ADDR(.flash.tbss);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   /* Marks the end of data, bss and possibly rodata */
@@ -494,6 +546,10 @@ SECTIONS
 
     mapping[extern_ram]
 
+    /* mutable libs begin */
+    mutable[extern_ram]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(4, _ext_ram_bss_end)
   } > extern_ram_seg
 #endif  //CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY

components/esp_system/ld/esp32c6/sections.ld.in

@@ -28,6 +28,10 @@ SECTIONS
 
     mapping[rtc_text]
 
+    /* mutable libs begin */
+    mutable[rtc_text]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.text .text.*)
     *(.rtc_text_end_test)
 
@@ -48,6 +52,10 @@ SECTIONS
 
     mapping[rtc_force_fast]
 
+    /* mutable libs begin */
+    mutable[rtc_force_fast]
+    /* mutable libs end */
+
     *(.rtc.force_fast .rtc.force_fast.*)
 
     ALIGNED_SYMBOL(4, _rtc_force_fast_end)
@@ -65,6 +73,10 @@ SECTIONS
 
     mapping[rtc_data]
 
+    /* mutable libs begin */
+    mutable[rtc_data]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.* .srodata.*)
 
     _rtc_data_end = ABSOLUTE(.);
@@ -80,6 +92,10 @@ SECTIONS
 
     mapping[rtc_bss]
 
+    /* mutable libs begin */
+    mutable[rtc_bss]
+    /* mutable libs end */
+
     _rtc_bss_end = ABSOLUTE(.);
   } > lp_ram_seg
 
@@ -192,6 +208,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > sram_seg
 
   /* Marks the end of IRAM code segment */
@@ -209,6 +230,10 @@ SECTIONS
 
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     _iram_data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -218,6 +243,10 @@ SECTIONS
 
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
 
     ALIGNED_SYMBOL(16, _iram_end)
@@ -237,6 +266,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -266,6 +300,10 @@ SECTIONS
      */
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > sram_seg
 
@@ -281,6 +319,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.linkonce.t.*)
     *(.gnu.warning)
@@ -383,6 +426,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
     . = ALIGN(ALIGNOF(SECTION_AFTER_FLASH_RODATA));
   } > default_rodata_seg
@@ -454,6 +502,10 @@ SECTIONS
     _rodata_reserved_end = ADDR(.flash.tbss);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   /* Marks the end of data, bss and possibly rodata */

components/esp_system/ld/esp32c61/sections.ld.in

@@ -37,6 +37,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > sram_seg
 
   /* Marks the end of IRAM code segment */
@@ -54,6 +59,10 @@ SECTIONS
 
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     _iram_data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -63,6 +72,10 @@ SECTIONS
 
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
     ALIGNED_SYMBOL(16, _iram_end)
   } > sram_seg
@@ -90,6 +103,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -119,6 +137,10 @@ SECTIONS
      */
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > sram_seg
 
@@ -136,6 +158,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.linkonce.t.*)
     *(.gnu.warning)
@@ -246,6 +273,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
     . = ALIGN(ALIGNOF(SECTION_AFTER_FLASH_RODATA));
   } > default_rodata_seg
@@ -325,6 +357,10 @@ SECTIONS
     _rodata_reserved_end = ADDR(.flash.tbss);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   /* Marks the end of data, bss and possibly rodata */
@@ -353,6 +389,10 @@ SECTIONS
 
     mapping[extern_ram]
 
+    /* mutable libs begin */
+    mutable[extern_ram]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(4, _ext_ram_bss_end)
   } > extern_ram_seg
 #endif  //CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY

components/esp_system/ld/esp32h2/sections.ld.in

@@ -28,6 +28,10 @@ SECTIONS
 
     mapping[rtc_text]
 
+    /* mutable libs begin */
+    mutable[rtc_text]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.text .text.*)
     *(.rtc_text_end_test)
 
@@ -48,6 +52,10 @@ SECTIONS
 
     mapping[rtc_force_fast]
 
+    /* mutable libs begin */
+    mutable[rtc_force_fast]
+    /* mutable libs end */
+
     *(.rtc.force_fast .rtc.force_fast.*)
 
     ALIGNED_SYMBOL(4, _rtc_force_fast_end)
@@ -65,6 +73,10 @@ SECTIONS
 
     mapping[rtc_data]
 
+    /* mutable libs begin */
+    mutable[rtc_data]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.* .srodata.*)
 
     _rtc_data_end = ABSOLUTE(.);
@@ -80,6 +92,10 @@ SECTIONS
 
     mapping[rtc_bss]
 
+    /* mutable libs begin */
+    mutable[rtc_bss]
+    /* mutable libs end */
+
     _rtc_bss_end = ABSOLUTE(.);
   } > lp_ram_seg
 
@@ -194,6 +210,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > sram_seg
 
   /* Marks the end of IRAM code segment */
@@ -211,6 +232,10 @@ SECTIONS
 
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     _iram_data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -220,6 +245,10 @@ SECTIONS
 
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
 
     ALIGNED_SYMBOL(16, _iram_end)
@@ -239,6 +268,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -268,6 +302,10 @@ SECTIONS
      */
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > sram_seg
 
@@ -283,6 +321,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.linkonce.t.*)
     *(.gnu.warning)
@@ -385,6 +428,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
     . = ALIGN(ALIGNOF(SECTION_AFTER_FLASH_RODATA));
   } > default_rodata_seg
@@ -456,6 +504,10 @@ SECTIONS
     _rodata_reserved_end = ADDR(.flash.tbss);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   /* Marks the end of data, bss and possibly rodata */

components/esp_system/ld/esp32h21/sections.ld.in

@@ -30,6 +30,10 @@ SECTIONS
 
     mapping[rtc_text]
 
+    /* mutable libs begin */
+    mutable[rtc_text]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.text .text.*)
     *(.rtc_text_end_test)
 
@@ -50,6 +54,10 @@ SECTIONS
 
     mapping[rtc_force_fast]
 
+    /* mutable libs begin */
+    mutable[rtc_force_fast]
+    /* mutable libs end */
+
     *(.rtc.force_fast .rtc.force_fast.*)
 
     ALIGNED_SYMBOL(4, _rtc_force_fast_end)
@@ -67,6 +75,10 @@ SECTIONS
 
     mapping[rtc_data]
 
+    /* mutable libs begin */
+    mutable[rtc_data]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.* .srodata.*)
 
     _rtc_data_end = ABSOLUTE(.);
@@ -82,6 +94,10 @@ SECTIONS
 
     mapping[rtc_bss]
 
+    /* mutable libs begin */
+    mutable[rtc_bss]
+    /* mutable libs end */
+
     _rtc_bss_end = ABSOLUTE(.);
   } > lp_ram_seg
 
@@ -183,6 +199,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > sram_seg
 
   /* Marks the end of IRAM code segment */
@@ -200,6 +221,10 @@ SECTIONS
 
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     _iram_data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -209,6 +234,10 @@ SECTIONS
 
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
 
     ALIGNED_SYMBOL(16, _iram_end)
@@ -228,6 +257,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -257,6 +291,10 @@ SECTIONS
      */
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > sram_seg
 
@@ -272,6 +310,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.linkonce.t.*)
     *(.gnu.warning)
@@ -374,6 +417,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
     . = ALIGN(ALIGNOF(SECTION_AFTER_FLASH_RODATA));
   } > default_rodata_seg
@@ -445,6 +493,10 @@ SECTIONS
     _rodata_reserved_end = ADDR(.flash.tbss);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   /* Marks the end of data, bss and possibly rodata */

components/esp_system/ld/esp32h4/sections.ld.in

@@ -27,6 +27,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > sram_seg
 
   /* Marks the end of IRAM code segment */
@@ -44,6 +49,10 @@ SECTIONS
 
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     _iram_data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -53,6 +62,10 @@ SECTIONS
 
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
     ALIGNED_SYMBOL(16, _iram_end)
   } > sram_seg
@@ -71,6 +84,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > sram_seg
 
@@ -100,6 +118,10 @@ SECTIONS
      */
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > sram_seg
 
@@ -117,6 +139,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.linkonce.t.*)
     *(.gnu.warning)
@@ -219,6 +246,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
     . = ALIGN(ALIGNOF(SECTION_AFTER_FLASH_RODATA));
   } > default_rodata_seg
@@ -290,6 +322,10 @@ SECTIONS
     _rodata_reserved_end = ADDR(.flash.tbss);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   /* Marks the end of data, bss and possibly rodata */

components/esp_system/ld/esp32p4/sections.ld.in

@@ -26,8 +26,13 @@ SECTIONS
     ALIGNED_SYMBOL(_esp_pmp_align_size, _rtc_text_start)
 
     arrays[rtc_text]
+
     mapping[rtc_text]
 
+    /* mutable libs begin */
+    mutable[rtc_text]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.text .text.*)
     *(.rtc_text_end_test)
 
@@ -47,8 +52,13 @@ SECTIONS
     ALIGNED_SYMBOL(4, _rtc_force_fast_start)
 
     arrays[rtc_force_fast]
+
     mapping[rtc_force_fast]
 
+    /* mutable libs begin */
+    mutable[rtc_force_fast]
+    /* mutable libs end */
+
     *(.rtc.force_fast .rtc.force_fast.*)
 
     ALIGNED_SYMBOL(4, _rtc_force_fast_end)
@@ -65,8 +75,13 @@ SECTIONS
     _rtc_data_start = ABSOLUTE(.);
 
     arrays[rtc_data]
+
     mapping[rtc_data]
 
+    /* mutable libs begin */
+    mutable[rtc_data]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.* .srodata.*)
 
     _rtc_data_end = ABSOLUTE(.);
@@ -81,8 +96,13 @@ SECTIONS
     *rtc_wake_stub*.*(COMMON)
 
     arrays[rtc_bss]
+
     mapping[rtc_bss]
 
+    /* mutable libs begin */
+    mutable[rtc_bss]
+    /* mutable libs end */
+
     _rtc_bss_end = ABSOLUTE(.);
   } > lp_ram_seg
 
@@ -163,8 +183,13 @@ SECTIONS
     _tcm_text_start = ABSOLUTE(.);
 
     arrays[tcm_text]
+
     mapping[tcm_text]
 
+    /* mutable libs begin */
+    mutable[tcm_text]
+    /* mutable libs end */
+
     _tcm_text_end = ABSOLUTE(.);
   } > tcm_idram_seg
 
@@ -173,8 +198,13 @@ SECTIONS
     _tcm_data_start = ABSOLUTE(.);
 
     arrays[tcm_data]
+
     mapping[tcm_data]
 
+    /* mutable libs begin */
+    mutable[tcm_data]
+    /* mutable libs end */
+
     _tcm_data_end = ABSOLUTE(.);
   } > tcm_idram_seg
 
@@ -190,8 +220,14 @@ SECTIONS
     _iram_text_start = ABSOLUTE(.);
 
     arrays[iram0_text]
+
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > sram_low
 
   /* Marks the end of IRAM code segment */
@@ -208,8 +244,13 @@ SECTIONS
     ALIGNED_SYMBOL(16, _iram_data_start)
 
     arrays[iram0_data]
+
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     _iram_data_end = ABSOLUTE(.);
   } > sram_low
 
@@ -218,8 +259,13 @@ SECTIONS
     ALIGNED_SYMBOL(16, _iram_bss_start)
 
     arrays[iram0_bss]
+
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
 
     ALIGNED_SYMBOL(16, _iram_end)
@@ -238,8 +284,14 @@ SECTIONS
     *(.jcr)
 
     arrays[dram0_data]
+
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end_low = ABSOLUTE(.);
   } > sram_low
 
@@ -249,6 +301,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end_high = ABSOLUTE(.);
   } > sram_high
 
@@ -278,8 +335,14 @@ SECTIONS
     _text_start = ABSOLUTE(.);
 
     arrays[flash_text]
+
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.linkonce.t.*)
     *(.gnu.warning)
@@ -360,6 +423,7 @@ SECTIONS
     _flash_rodata_start = ABSOLUTE(.);
 
     arrays[flash_rodata]
+
     mapping[flash_rodata]
 
     *(.irom1.text) /* catch stray ICACHE_RODATA_ATTR */
@@ -396,6 +460,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
     . = ALIGN(ALIGNOF(SECTION_AFTER_FLASH_RODATA));
   } > rodata_seg_low
@@ -475,7 +544,13 @@ SECTIONS
     _rodata_reserved_end = ADDR(.flash.tbss);
 
     arrays[rodata_noload]
+
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
+
   } > rodata_seg_low
 
 #if CONFIG_SPIRAM_XIP_FROM_PSRAM
@@ -495,8 +570,15 @@ SECTIONS
   .ext_ram.bss (NOLOAD) :
   {
     _ext_ram_bss_start = ABSOLUTE(.);
+
     arrays[extern_ram]
+
     mapping[extern_ram]
+
+    /* mutable libs begin */
+    mutable[extern_ram]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(4, _ext_ram_bss_end)
   } > ext_ram_seg
 #endif  //CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY
@@ -525,8 +607,13 @@ SECTIONS
      * (See components/esp_system/app.lf).
      */
     arrays[dram0_bss]
+
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(4, _bss_end_low)
   } > sram_low
 
@@ -540,6 +627,10 @@ SECTIONS
      */
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(4, _bss_end_high)
   } > sram_high
 

components/esp_system/ld/esp32s2/sections.ld.in

@@ -30,6 +30,10 @@ SECTIONS
 
     mapping[rtc_text]
 
+    /* mutable libs begin */
+    mutable[rtc_text]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.literal .text .literal.* .text.*)
 
     HIDDEN(_rtc_code_end = .);
@@ -65,6 +69,10 @@ SECTIONS
 
     mapping[rtc_force_fast]
 
+    /* mutable libs begin */
+    mutable[rtc_force_fast]
+    /* mutable libs end */
+
     *(.rtc.force_fast .rtc.force_fast.*)
 
     ALIGNED_SYMBOL(4, _rtc_force_fast_end)
@@ -84,6 +92,10 @@ SECTIONS
 
     mapping[rtc_data]
 
+    /* mutable libs begin */
+    mutable[rtc_data]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.*)
 
     _rtc_data_end = ABSOLUTE(.);
@@ -99,6 +111,10 @@ SECTIONS
 
     mapping[rtc_bss]
 
+    /* mutable libs begin */
+    mutable[rtc_bss]
+    /* mutable libs end */
+
     _rtc_bss_end = ABSOLUTE(.);
   } > rtc_data_location
 
@@ -213,6 +229,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     /* Padding for possible CPU prefetch + alignment for PMS split lines */
     . += _esp_memprot_prefetch_pad_size;
     . = ALIGN(_esp_memprot_align_size);
@@ -241,6 +262,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > dram0_0_seg
 
@@ -267,6 +293,10 @@ SECTIONS
 
     mapping[extern_ram]
 
+    /* mutable libs begin */
+    mutable[extern_ram]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(4, _ext_ram_bss_end)
   } > extern_ram_seg
 #endif //CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY
@@ -297,6 +327,10 @@ SECTIONS
      */
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > dram0_0_seg
 
@@ -380,6 +414,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
 
     /* Literals are also RO data. */
@@ -414,6 +453,10 @@ SECTIONS
     _rodata_reserved_end = ABSOLUTE(.);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   .flash.text :
@@ -428,6 +471,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.warning)
     *(.gnu.linkonce.literal.* .gnu.linkonce.t.*.literal .gnu.linkonce.t.*)

components/esp_system/ld/esp32s3/sections.ld.in

@@ -26,6 +26,10 @@ SECTIONS
 
     mapping[rtc_text]
 
+    /* mutable libs begin */
+    mutable[rtc_text]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.literal .text .literal.* .text.*)
     *(.rtc_text_end_test)
 
@@ -49,6 +53,10 @@ SECTIONS
 
     mapping[rtc_force_fast]
 
+    /* mutable libs begin */
+    mutable[rtc_force_fast]
+    /* mutable libs end */
+
     *(.rtc.force_fast .rtc.force_fast.*)
 
     ALIGNED_SYMBOL(4, _rtc_force_fast_end)
@@ -68,6 +76,10 @@ SECTIONS
 
     mapping[rtc_data]
 
+    /* mutable libs begin */
+    mutable[rtc_data]
+    /* mutable libs end */
+
     *rtc_wake_stub*.*(.data .rodata .data.* .rodata.*)
 
     _rtc_data_end = ABSOLUTE(.);
@@ -83,6 +95,10 @@ SECTIONS
 
     mapping[rtc_bss]
 
+    /* mutable libs begin */
+    mutable[rtc_bss]
+    /* mutable libs end */
+
     _rtc_bss_end = ABSOLUTE(.);
   } > rtc_data_location
 
@@ -197,6 +213,11 @@ SECTIONS
 
     mapping[iram0_text]
 
+    /* mutable libs begin */
+    mutable[iram0_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
   } > iram0_0_seg
 
   /**
@@ -221,6 +242,11 @@ SECTIONS
 
     mapping[dram0_data]
 
+    /* mutable libs begin */
+    mutable[dram0_data]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _data_end = ABSOLUTE(.);
   } > dram0_0_seg
 
@@ -250,6 +276,10 @@ SECTIONS
      */
     mapping[dram0_bss]
 
+    /* mutable libs begin */
+    mutable[dram0_bss]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(8, _bss_end)
   } > dram0_0_seg
 
@@ -268,6 +298,11 @@ SECTIONS
 
     mapping[flash_text]
 
+    /* mutable libs begin */
+    mutable[flash_text]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     *(.stub)
     *(.gnu.warning)
     *(.gnu.linkonce.literal.* .gnu.linkonce.t.*.literal .gnu.linkonce.t.*)
@@ -391,6 +426,11 @@ SECTIONS
     KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
     _esp_system_init_fn_array_end = ABSOLUTE(.);
 
+    /* mutable libs begin */
+    mutable[flash_rodata]
+    FAST_REFLASHING_PADDING;
+    /* mutable libs end */
+
     _rodata_end = ABSOLUTE(.);
 
     /* Literals are also RO data. */
@@ -425,6 +465,10 @@ SECTIONS
     _rodata_reserved_end = ABSOLUTE(.);
 
     mapping[rodata_noload]
+
+    /* mutable libs begin */
+    mutable[rodata_noload]
+    /* mutable libs end */
   } > default_rodata_seg
 
   /**
@@ -446,6 +490,10 @@ SECTIONS
 
     mapping[extern_ram]
 
+    /* mutable libs begin */
+    mutable[extern_ram]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(4, _ext_ram_bss_end)
   } > extern_ram_seg
 #endif //CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY
@@ -484,6 +532,10 @@ SECTIONS
 
     mapping[iram0_data]
 
+    /* mutable libs begin */
+    mutable[iram0_data]
+    /* mutable libs end */
+
     ALIGNED_SYMBOL(4, _iram_data_end)
   } > iram0_0_seg
 
@@ -493,6 +545,10 @@ SECTIONS
 
     mapping[iram0_bss]
 
+    /* mutable libs begin */
+    mutable[iram0_bss]
+    /* mutable libs end */
+
     _iram_bss_end = ABSOLUTE(.);
     ALIGNED_SYMBOL(4, _iram_end)
   } > iram0_0_seg

components/esp_system/ld/ld.common

@@ -94,3 +94,23 @@ ASSERT((ADDR(NEXT_SECTION) == ADDR(PREV_SECTION) + SIZEOF(PREV_SECTION)), \
 #else
 #define SECTION_AFTER_FLASH_RODATA .flash.tdata
 #endif
+
+/*
+ * FAST_REFLASHING_PADDING
+ *
+ * Aligns the current location (.) to CONFIG_ESPTOOLPY_FAST_REFLASHING_PADDING.
+ * If more than half of the alignment block is already consumed,
+ * extra padding is applied to skip to the next boundary.
+ * For example, if the current location (.) is 0x1900 and the padding is 4 KB,
+ * the location will be moved to 0x3000 instead of 0x2000 because less than
+ * half of the current 4 KB block remains (0x2000 - 0x1900 < 2 KB).
+ */
+#if CONFIG_ESPTOOLPY_FAST_REFLASHING
+#define FAST_REFLASHING_PADDING \
+  . = ALIGN((. + ( \
+    (CONFIG_ESPTOOLPY_FAST_REFLASHING_PADDING - (ALIGN(CONFIG_ESPTOOLPY_FAST_REFLASHING_PADDING) - .)) + \
+    (CONFIG_ESPTOOLPY_FAST_REFLASHING_PADDING / 2) \
+  )), CONFIG_ESPTOOLPY_FAST_REFLASHING_PADDING)
+#else
+#define FAST_REFLASHING_PADDING
+#endif

components/esptool_py/Kconfig.projbuild

@@ -202,4 +202,65 @@ menu "Serial flasher config"
         int
         default ESP_CONSOLE_UART_BAUDRATE if ESP_CONSOLE_UART
         default 115200 if !ESP_CONSOLE_UART
+
+    menu "Fast Reflashing"
+
+        config ESPTOOLPY_FAST_REFLASHING
+            bool "Enable fast reflashing (Experimental)"
+            depends on IDF_EXPERIMENTAL_FEATURES
+            select COMPILER_NO_MERGE_CONSTANTS if IDF_TOOLCHAIN_GCC
+            help
+                Enabling this option classifies component libraries into two
+                categories: mutable and immutable. Mutable libraries are
+                expected to change frequently during development, while
+                immutable libraries are considered stable. All project
+                component libraries are treated as mutable; all other libraries
+                are treated as immutable.
+
+                In the generated linker script, input sections from immutable
+                libraries are placed before those from mutable libraries. This
+                layout helps localize changes in the output sections of the ELF
+                file, so that recompilation primarily affects a confined area
+                associated with the mutable libraries.
+
+                This enables the generation of binary images with large
+                unmodified regions across recompilations, allowing to flash
+                only the parts that have changed.
+
+                To support this, some compiler optimizations, such as constant
+                merging, are disabled, which helps minimize differences in the
+                binary image between builds.  However, this may increase the
+                overall image size and flash usage.
+
+                Additionally, this option inserts a padding, defined by the
+                ESPTOOLPY_FAST_REFLASHING_PADDING option, after the input
+                sections of mutable libraries. This allows further isolate
+                changes but also increases the size of the binary image and
+                flash consumption.
+
+        choice ESPTOOLPY_FAST_REFLASHING_PADDING_SIZE
+            prompt "Padding size"
+            default ESPTOOLPY_FAST_REFLASHING_PADDING_4KB
+            depends on ESPTOOLPY_FAST_REFLASHING
+            help
+                Selects the amount of padding (in kilobytes) to add after input
+                sections of mutable libraries when fast reflashing is enabled.
+
+            config ESPTOOLPY_FAST_REFLASHING_PADDING_2KB
+                bool "2 KB"
+            config ESPTOOLPY_FAST_REFLASHING_PADDING_4KB
+                bool "4 KB"
+            config ESPTOOLPY_FAST_REFLASHING_PADDING_8KB
+                bool "8 KB"
+        endchoice
+
+        config ESPTOOLPY_FAST_REFLASHING_PADDING
+            int
+            depends on ESPTOOLPY_FAST_REFLASHING
+            default 2048 if ESPTOOLPY_FAST_REFLASHING_PADDING_2KB
+            default 4096 if ESPTOOLPY_FAST_REFLASHING_PADDING_4KB
+            default 8192 if ESPTOOLPY_FAST_REFLASHING_PADDING_8KB
+
+    endmenu
+
 endmenu

tools/cmake/ldgen.cmake

@@ -88,6 +88,32 @@ function(__ldgen_get_lib_deps_of_target target out_list_var)
     set(${out_list_var} ${out_list} PARENT_SCOPE)
 endfunction()
 
+# __ldgen_get_mutable_libs
+#
+# Helper function to get the list of library file name generator expressions
+# for project components. These libraries are placed by ldgen into a separate
+# location in the linker script, allowing the fast reflashing feature.
+#
+function(__ldgen_get_mutable_libs out_list_var)
+    set(mutable_libs)
+    idf_build_get_property(build_component_targets __BUILD_COMPONENT_TARGETS)
+    foreach(component_target ${build_component_targets})
+        __component_get_property(component_source ${component_target} COMPONENT_SOURCE)
+        __component_get_property(component_lib ${component_target} COMPONENT_LIB)
+        __component_get_property(component_type ${component_target} COMPONENT_TYPE)
+        if("${component_type}" STREQUAL "CONFIG_ONLY")
+            # Configuration only component interface target without a library.
+            continue()
+        endif()
+        if(NOT "${component_source}" STREQUAL "project_components")
+            # Add only project components as mutable.
+            continue()
+        endif()
+        set(unstable_lib "$<TARGET_LINKER_FILE_NAME:${component_lib}>")
+        list(APPEND mutable_libs "${unstable_lib}")
+    endforeach()
+    set(${out_list_var} ${mutable_libs} PARENT_SCOPE)
+endfunction()
 
 # __ldgen_create_target
 #
@@ -177,6 +203,17 @@ function(__ldgen_create_target exe_target)
         message(STATUS "Mapping check enabled in ldgen")
     endif()
 
+    if(CONFIG_ESPTOOLPY_FAST_REFLASHING)
+        # Create a file containing a list of mutable libraries used by ldgen
+        # for fast reflashing.
+        set(mutable_libs_path "${build_dir}/ldgen_mutable_libraries")
+        __ldgen_get_mutable_libs(mutable_libs)
+        list(JOIN mutable_libs "\n" mutable_libs_str)
+        file(GENERATE OUTPUT "${mutable_libs_path}"
+            CONTENT "${mutable_libs_str}")
+        set(mutable_libs_option "--mutable-libraries-file" "${mutable_libs_path}")
+    endif()
+
     add_custom_command(
         OUTPUT ${output}
         COMMAND ${python} "${idf_path}/tools/ldgen/ldgen.py"
@@ -189,6 +226,7 @@ function(__ldgen_create_target exe_target)
         --libraries-file "${build_dir}/ldgen_libraries"
         --objdump   "${CMAKE_OBJDUMP}"
         ${ldgen_check}
+        ${mutable_libs_option}
         DEPENDS     ${template} ${ldgen_fragment_files} ${ldgen_deps} ${SDKCONFIG}
         VERBATIM
     )

tools/ldgen/ldgen.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 #
-# SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
+# SPDX-FileCopyrightText: 2021-2025 Espressif Systems (Shanghai) CO LTD
 # SPDX-License-Identifier: Apache-2.0
 #
 import argparse
@@ -23,7 +23,7 @@ from pyparsing import ParseFatalException
 
 
 def _update_environment(args):
-    env = [(name, value) for (name,value) in (e.split('=',1) for e in args.env)]
+    env = [(name, value) for (name, value) in (e.split('=', 1) for e in args.env)]
     for name, value in env:
         value = ' '.join(value.split())
         os.environ[name] = value
@@ -34,76 +34,69 @@ def _update_environment(args):
 
 
 def main():
-
     argparser = argparse.ArgumentParser(description='ESP-IDF linker script generator')
 
-    argparser.add_argument(
+    argparser.add_argument('--input', '-i', help='Linker template file', type=argparse.FileType('r'))
-        '--input', '-i',
-        help='Linker template file',
-        type=argparse.FileType('r'))
 
     fragments_group = argparser.add_mutually_exclusive_group()
 
     fragments_group.add_argument(
-        '--fragments', '-f',
+        '--fragments', '-f', type=argparse.FileType('r'), help='Input fragment files', nargs='+'
-        type=argparse.FileType('r'),
-        help='Input fragment files',
-        nargs='+'
     )
 
     fragments_group.add_argument(
-        '--fragments-list',
+        '--fragments-list', help='Input fragment files as a semicolon-separated list', type=str
-        help='Input fragment files as a semicolon-separated list',
-        type=str
     )
 
     argparser.add_argument(
-        '--libraries-file',
+        '--libraries-file', type=argparse.FileType('r'), help='File that contains the list of libraries in the build'
+    )
+
+    argparser.add_argument(
+        '--mutable-libraries-file',
         type=argparse.FileType('r'),
-        help='File that contains the list of libraries in the build')
+        help='File that contains the list of mutable libraries in the build',
+    )
+
+    argparser.add_argument('--output', '-o', help='Output linker script', type=str)
+
+    argparser.add_argument('--config', '-c', help='Project configuration')
+
+    argparser.add_argument('--kconfig', '-k', help='IDF Kconfig file')
 
     argparser.add_argument(
-        '--output', '-o',
+        '--check-mapping', help='Perform a check if a mapping (archive, obj, symbol) exists', action='store_true'
-        help='Output linker script',
-        type=str)
-
-    argparser.add_argument(
-        '--config', '-c',
-        help='Project configuration')
-
-    argparser.add_argument(
-        '--kconfig', '-k',
-        help='IDF Kconfig file')
-
-    argparser.add_argument(
-        '--check-mapping',
-        help='Perform a check if a mapping (archive, obj, symbol) exists',
-        action='store_true'
     )
 
     argparser.add_argument(
-        '--check-mapping-exceptions',
+        '--check-mapping-exceptions', help='Mappings exempted from check', type=argparse.FileType('r')
-        help='Mappings exempted from check',
-        type=argparse.FileType('r')
     )
 
     argparser.add_argument(
-        '--env', '-e',
+        '--env',
-        action='append', default=[],
+        '-e',
-        help='Environment to set when evaluating the config file', metavar='NAME=VAL')
+        action='append',
-
+        default=[],
-    argparser.add_argument('--env-file', type=argparse.FileType('r'),
+        help='Environment to set when evaluating the config file',
-                           help='Optional file to load environment variables from. Contents '
+        metavar='NAME=VAL',
-                           'should be a JSON object where each key/value pair is a variable.')
+    )
 
     argparser.add_argument(
-        '--objdump',
+        '--env-file',
-        help='Path to toolchain objdump')
+        type=argparse.FileType('r'),
+        help='Optional file to load environment variables from. Contents '
+        'should be a JSON object where each key/value pair is a variable.',
+    )
+
+    argparser.add_argument('--objdump', help='Path to toolchain objdump')
+
+    argparser.add_argument('--debug', '-d', help='Print debugging information.', action='store_true')
 
     args = argparser.parse_args()
 
     input_file = args.input
     libraries_file = args.libraries_file
+    mutable_libraries_file = args.mutable_libraries_file or []
     config_file = args.config
     output_path = args.output
     kconfig_file = args.kconfig
@@ -132,7 +125,8 @@ def main():
                 dump.name = library
                 sections_infos.add_sections_info(dump)
 
-        generation_model = Generation(check_mapping, check_mapping_exceptions)
+        mutable_libs = [lib.strip() for lib in mutable_libraries_file]
+        generation_model = Generation(check_mapping, check_mapping_exceptions, mutable_libs, args.debug)
 
         _update_environment(args)  # assign args.env and args.env_file to os.environ
 
@@ -145,7 +139,7 @@ def main():
                 # ParseException is raised on incorrect grammar
                 # ParseFatalException is raised on correct grammar, but inconsistent contents (ex. duplicate
                 # keys, key unsupported by fragment, unexpected number of values, etc.)
-                raise LdGenFailure('failed to parse %s\n%s' % (fragment_file, str(e)))
+                raise LdGenFailure(f'failed to parse {fragment_file}\n{e}')
             generation_model.add_fragments_from_file(fragment_file)
 
         non_contiguous_sram = sdkconfig.evaluate_expression('SOC_MEM_NON_CONTIGUOUS_SRAM')
@@ -165,10 +159,12 @@ def main():
                     if exc.errno != errno.EEXIST:
                         raise
 
-            with open(output_path, 'w', encoding='utf-8') as f:  # only create output file after generation has succeeded
+            with open(
+                output_path, 'w', encoding='utf-8'
+            ) as f:  # only create output file after generation has succeeded
                 f.write(output.read())
     except LdGenFailure as e:
-        print('linker script generation failed for %s\nERROR: %s' % (input_file.name, e))
+        print(f'linker script generation failed for {input_file.name}\nERROR: {e}')
         sys.exit(1)
 
 

tools/ldgen/ldgen/generation.py

@@ -41,7 +41,7 @@ class Placement:
     for details).
     """
 
-    def __init__(self, node, sections, target, flags, explicit, force=False, dryrun=False):
+    def __init__(self, node, sections, target, flags, explicit, force=False, dryrun=False, mutable=False):
         self.node = node
         self.sections = sections
         self.target = target
@@ -57,6 +57,10 @@ class Placement:
         # fragment entry.
         self.explicit = explicit
 
+        # This placement is designated as mutable and should be assigned to a
+        # mutable target.
+        self.mutable = mutable
+
         # Find basis placement.
         parent = node.parent
         candidate = None
@@ -83,11 +87,19 @@ class Placement:
         #
         # Placement can also be a basis if it has flags
         # (self.flags) or its basis has flags (self.basis.flags)
-        significant = (not self.basis or
+        #
-                       self.target != self.basis.target or
+        # The mutable placement mark is used to place the placement within a
-                       (self.flags and not self.basis.flags) or
+        # designated area (MutableMarker) in the linker script. If the basis is
-                       (not self.flags and self.basis.flags) or
+        # also mutable, the placement is deemed insignificant to prevent adding
-                       self.force)
+        # unnecessary EXCLUDE_FILE and placement rules to the linker script.
+        significant = (
+            not self.basis
+            or self.target != self.basis.target
+            or (self.flags and not self.basis.flags)
+            or (not self.flags and self.basis.flags)
+            or (self.mutable and not self.basis.mutable)
+            or self.force
+        )
 
         if significant and not self.explicit and not self.sections:
             # The placement is significant, but it is an intermediate placement
@@ -112,6 +124,15 @@ class Placement:
     def add_subplacement(self, subplacement):
         self.subplacements.add(subplacement)
 
+    def __str__(self):
+        sections_str = ', '.join(self.sections)
+        basis_str = self.basis.node.name if self.basis else 'NONE'
+        return (
+            f'({sections_str} -> {self.target}), basis: {basis_str}, '
+            f'force: {self.force}, stable: {self.stable}, '
+            f'explicit: {self.explicit}, flags: {self.flags}'
+        )
+
 
 class EntityNode:
     """
@@ -155,7 +176,7 @@ class EntityNode:
         assert name and name != Entity.ALL
 
         child = [c for c in self.children if c.name == name]
-        assert (len(child) <= 1)
+        assert len(child) <= 1
 
         if not child:
             child = self.child_t(self, name)
@@ -169,7 +190,7 @@ class EntityNode:
         commands = collections.defaultdict(list)
 
         def process_commands(cmds):
-            for (target, commands_list) in cmds.items():
+            for target, commands_list in cmds.items():
                 commands[target].extend(commands_list)
 
         # Process the commands generated from this node
@@ -196,6 +217,7 @@ class EntityNode:
                 keep = False
                 sort = None
                 surround_type = []
+                mutable = placement.mutable
 
                 placement_flags = placement.flags if placement.flags is not None else []
 
@@ -212,52 +234,70 @@ class EntityNode:
                 for flag in surround_type:
                     if flag.pre:
                         if isinstance(flag, Surround):
-                            commands[placement.target].append(SymbolAtAddress(f'_{flag.symbol}_start', tied))
+                            commands[placement.target].append(
+                                SymbolAtAddress(f'_{flag.symbol}_start', tied, mutable=mutable)
+                            )
                         else:  # ALIGN
-                            commands[placement.target].append(AlignAtAddress(flag.alignment, tied))
+                            commands[placement.target].append(AlignAtAddress(flag.alignment, tied, mutable=mutable))
 
                 # This is for expanded object node and symbol node placements without checking for
                 # the type.
                 placement_sections = frozenset(placement.sections)
                 command_sections = sections if sections == placement_sections else placement_sections
 
-                command = InputSectionDesc(placement.node.entity, command_sections,
+                command = InputSectionDesc(
-                                           [e.node.entity for e in placement.exclusions], keep, sort, tied)
+                    placement.node.entity,
+                    command_sections,
+                    [e.node.entity for e in placement.exclusions],
+                    keep,
+                    sort,
+                    tied,
+                    mutable=mutable,
+                )
                 commands[placement.target].append(command)
 
                 # Generate commands for intermediate, non-explicit exclusion placements here,
                 # so that they can be enclosed by flags that affect the parent placement.
                 for subplacement in placement.subplacements:
                     if not subplacement.flags and not subplacement.explicit:
-                        command = InputSectionDesc(subplacement.node.entity, subplacement.sections,
+                        command = InputSectionDesc(
-                                                   [e.node.entity for e in subplacement.exclusions], keep, sort, tied)
+                            subplacement.node.entity,
+                            subplacement.sections,
+                            [e.node.entity for e in subplacement.exclusions],
+                            keep,
+                            sort,
+                            tied,
+                            mutable=mutable,
+                        )
                         commands[placement.target].append(command)
 
                 for flag in surround_type:
                     if flag.post:
                         if isinstance(flag, Surround):
-                            commands[placement.target].append(SymbolAtAddress(f'_{flag.symbol}_end', tied))
+                            commands[placement.target].append(
+                                SymbolAtAddress(f'_{flag.symbol}_end', tied, mutable=mutable)
+                            )
                         else:  # ALIGN
-                            commands[placement.target].append(AlignAtAddress(flag.alignment, tied))
+                            commands[placement.target].append(AlignAtAddress(flag.alignment, tied, mutable=mutable))
 
         return commands
 
-    def self_placement(self, sections, target, flags, explicit=True, force=False):
+    def self_placement(self, sections, target, flags, explicit=True, force=False, mutable=False):
-        placement = Placement(self, sections, target, flags, explicit, force)
+        placement = Placement(self, sections, target, flags, explicit, force=force, mutable=mutable)
         self.placements[sections] = placement
         return placement
 
-    def child_placement(self, entity, sections, target, flags, sections_db):
+    def child_placement(self, entity, sections, target, flags, mutable, sections_db):
         child = self.add_child(entity)
-        child.insert(entity, sections, target, flags, sections_db)
+        child.insert(entity, sections, target, flags, mutable, sections_db)
 
-    def insert(self, entity, sections, target, flags, sections_db):
+    def insert(self, entity, sections, target, flags, mutable, sections_db):
         if self.entity.specificity == entity.specificity:
             # Since specificities match, create the placement in this node.
-            self.self_placement(sections, target, flags)
+            self.self_placement(sections, target, flags, mutable=mutable)
         else:
             # If not, create a child node and try to create the placement there.
-            self.child_placement(entity, sections, target, flags, sections_db)
+            self.child_placement(entity, sections, target, flags, mutable, sections_db)
 
     def get_output_sections(self):
         return sorted(self.placements.keys(), key=lambda x: sorted(x))  # pylint: disable=W0108
@@ -298,9 +338,9 @@ class ObjectNode(EntityNode):
         self.entity = Entity(self.parent.name, self.name)
         self.subplacements = list()
 
-    def child_placement(self, entity, sections, target, flags, sections_db):
+    def child_placement(self, entity, sections, target, flags, mutable, sections_db):
         child = self.add_child(entity)
-        sym_placement = Placement(child, sections, target, flags, True, dryrun=True)
+        sym_placement = Placement(child, sections, target, flags, True, dryrun=True, mutable=mutable)
 
         # The basis placement for sym_placement can either be
         # an existing placement on this node, or nonexistent.
@@ -319,7 +359,7 @@ class ObjectNode(EntityNode):
 
             if obj_sections:
                 symbol = entity.symbol
-                remove_sections = [s.replace('.*', '.%s' % symbol) for s in sections if '.*' in s]
+                remove_sections = [s.replace('.*', f'.{symbol}') for s in sections if '.*' in s]
                 filtered_sections = [s for s in obj_sections if s not in remove_sections]
 
                 if set(filtered_sections) != set(obj_sections):
@@ -331,7 +371,9 @@ class ObjectNode(EntityNode):
                             obj_placement = self.placements[sections]
                         except KeyError:
                             # Create intermediate placement.
-                            obj_placement = self.self_placement(sections, sym_placement.basis.target, None, False)
+                            obj_placement = self.self_placement(
+                                sections, sym_placement.basis.target, None, False, mutable=mutable
+                            )
                             if obj_placement.basis.flags:
                                 subplace = True
 
@@ -383,12 +425,13 @@ class Generation:
     """
 
     # Processed mapping, scheme and section entries
-    EntityMapping = namedtuple('EntityMapping', 'entity sections_group target flags')
+    EntityMapping = namedtuple('EntityMapping', 'entity sections_group target flags mutable')
 
-    def __init__(self, check_mappings=False, check_mapping_exceptions=None):
+    def __init__(self, check_mappings=False, check_mapping_exceptions=None, mutable_libs=None, debug=False):
         self.schemes = {}
         self.placements = {}
         self.mappings = {}
+        self.debug = debug
 
         self.check_mappings = check_mappings
 
@@ -397,6 +440,11 @@ class Generation:
         else:
             self.check_mapping_exceptions = []
 
+        if mutable_libs is None:
+            self.mutable_libs = []
+        else:
+            self.mutable_libs = mutable_libs
+
     def _prepare_scheme_dictionary(self):
         scheme_dictionary = collections.defaultdict(dict)
 
@@ -404,7 +452,7 @@ class Generation:
         for scheme in self.schemes.values():
             sections_bucket = collections.defaultdict(list)
 
-            for (sections_name, target_name) in scheme.entries:
+            for sections_name, target_name in scheme.entries:
                 # Get the sections under the bucket 'target_name'. If this bucket does not exist
                 # is created automatically
                 sections_in_bucket = sections_bucket[target_name]
@@ -420,7 +468,7 @@ class Generation:
             scheme_dictionary[scheme.name] = sections_bucket
 
         # Search for and raise exception on first instance of sections mapped to multiple targets
-        for (scheme_name, sections_bucket) in scheme_dictionary.items():
+        for scheme_name, sections_bucket in scheme_dictionary.items():
             for sections_a, sections_b in itertools.combinations(sections_bucket.values(), 2):
                 set_a = set()
                 set_b = set()
@@ -442,26 +490,59 @@ class Generation:
 
         return scheme_dictionary
 
+    def _get_section_strs(self, section):
+        s_list = [Sections.get_section_data_from_entry(s) for s in section.entries]
+        return frozenset([item for sublist in s_list for item in sublist])
+
+    def _prepare_mutable_entity_mappings(self, entity_mappings, scheme_dictionary, entities):
+        # Go through all mutable libraries, if any, and add entity mapping for
+        # each "default" section set for which the entity mapping does not yet
+        # exist.  This adds mapping for every mutable library as if specified in
+        # the mapping fragment. All newly added or existing entity mappings
+        # related to mutable libraries are marked as mutable. This flag is used
+        # when the placement for it is created in the entity tree, ensuring the
+        # placement is forced to be emitted in the linker script and not
+        # considered non-significant.
+
+        for archive in self.mutable_libs:
+            entity = Entity(archive, '*')
+            for target, sections in scheme_dictionary['default'].items():
+                for section in sections:
+                    sections_str = self._get_section_strs(section)
+                    key = (entity, sections_str)
+                    if entity_mappings.get(key):
+                        # Mutable library already has entity mapping.
+                        continue
+
+                    entity_mappings[key] = Generation.EntityMapping(entity, sections_str, target, [], True)
+
+        for key, mapping in entity_mappings.items():
+            (entity, sections, target, flags, mutable) = mapping
+            if entity.archive not in self.mutable_libs or mutable:
+                # The entity either does not belong to a mutable library or is
+                # an archive entity that has already been marked as mutable.
+                continue
+            # Set entity as mutable.
+            entity_mappings[key] = Generation.EntityMapping(entity, sections, target, flags, True)
+
     def _prepare_entity_mappings(self, scheme_dictionary, entities):
         # Prepare entity mappings processed from mapping fragment entries.
-        def get_section_strs(section):
-            s_list = [Sections.get_section_data_from_entry(s) for s in section.entries]
-            return frozenset([item for sublist in s_list for item in sublist])
-
         entity_mappings = dict()
 
         for mapping in self.mappings.values():
             archive = mapping.archive
 
-            for (obj, symbol, scheme_name) in mapping.entries:
+            for obj, symbol, scheme_name in mapping.entries:
                 entity = Entity(archive, obj, symbol)
 
                 # Check the entity exists
-                if (self.check_mappings
+                if (
-                        and entity.specificity.value > Entity.Specificity.ARCHIVE.value
+                    self.check_mappings
-                        and mapping.name not in self.check_mapping_exceptions):
+                    and entity.specificity.value > Entity.Specificity.ARCHIVE.value
+                    and mapping.name not in self.check_mapping_exceptions
+                ):
                     if not entities.check_exists(entity):
-                        message = "'%s' not found" % str(entity)
+                        message = f"'{entity}' not found"
                         raise GenerationException(message, mapping)
 
                 if (obj, symbol, scheme_name) in mapping.flags.keys():
@@ -469,16 +550,16 @@ class Generation:
                     # Check if all section->target defined in the current
                     # scheme.
                     for flag in flags:
-                        if (flag.target not in scheme_dictionary[scheme_name].keys()
+                        if flag.target not in scheme_dictionary[scheme_name].keys() or flag.section not in [
-                                or flag.section not in
+                            _s.name for _s in scheme_dictionary[scheme_name][flag.target]
-                                [_s.name for _s in scheme_dictionary[scheme_name][flag.target]]):
+                        ]:
-                            message = "%s->%s not defined in scheme '%s'" % (flag.section, flag.target, scheme_name)
+                            message = f"{flag.section}->{flag.target} not defined in scheme '{scheme_name}'"
                             raise GenerationException(message, mapping)
                 else:
                     flags = None
 
                 # Create placement for each 'section -> target' in the scheme.
-                for (target, sections) in scheme_dictionary[scheme_name].items():
+                for target, sections in scheme_dictionary[scheme_name].items():
                     for section in sections:
                         # Find the applicable flags
                         _flags = []
@@ -488,7 +569,7 @@ class Generation:
                                 if (flag.section, flag.target) == (section.name, target):
                                     _flags.extend(flag.flags)
 
-                        sections_str = get_section_strs(section)
+                        sections_str = self._get_section_strs(section)
 
                         key = (entity, sections_str)
 
@@ -498,7 +579,7 @@ class Generation:
                             existing = None
 
                         if not existing:
-                            entity_mappings[key] = Generation.EntityMapping(entity, sections_str, target, _flags)
+                            entity_mappings[key] = Generation.EntityMapping(entity, sections_str, target, _flags, False)
                         else:
                             # Check for conflicts.
                             if target != existing.target:
@@ -509,31 +590,46 @@ class Generation:
                             if _flags or existing.flags:
                                 if (_flags and not existing.flags) or (not _flags and existing.flags):
                                     _flags.extend(existing.flags)
-                                    entity_mappings[key] = Generation.EntityMapping(entity,
+                                    entity_mappings[key] = Generation.EntityMapping(
-                                                                                    sections_str,
+                                        entity, sections_str, target, _flags, False
-                                                                                    target, _flags)
+                                    )
                                 elif _flags == existing.flags:
                                     pass
                                 else:
                                     raise GenerationException('Conflicting flags specified.', mapping)
 
+        # Add new mappings for mutable libraries and modify existing ones if
+        # they pertain to them.
+        self._prepare_mutable_entity_mappings(entity_mappings, scheme_dictionary, entities)
+
         # Sort the mappings by specificity, so as to simplify
         # insertion logic.
         res = list(entity_mappings.values())
         res.sort(key=lambda m: m.entity)
         return res
 
+    def _dump_entity_tree(self, node, indent=''):
+        print(f'{indent}-> {node.name}')
+        for placement in node.placements.values():
+            print(f'{indent}     {placement}')
+        print()
+        for child in node.children:
+            self._dump_entity_tree(child, ' ' * 8 + indent)
+
     def generate(self, entities, non_contiguous_sram):
         scheme_dictionary = self._prepare_scheme_dictionary()
         entity_mappings = self._prepare_entity_mappings(scheme_dictionary, entities)
         root_node = RootNode()
         for mapping in entity_mappings:
-            (entity, sections, target, flags) = mapping
+            (entity, sections, target, flags, mutable) = mapping
             try:
-                root_node.insert(entity, sections, target, flags, entities)
+                root_node.insert(entity, sections, target, flags, mutable, entities)
             except ValueError as e:
                 raise GenerationException(str(e))
 
+        if self.debug:
+            self._dump_entity_tree(root_node)
+
         # Traverse the tree, creating the placements
         commands = root_node.get_output_commands(non_contiguous_sram)
 
@@ -552,8 +648,7 @@ class Generation:
             if fragment.name in dict_to_append_to:
                 stored = dict_to_append_to[fragment.name].path
                 new = fragment.path
-                message = "Duplicate definition of fragment '%s' found in %s and %s." % (
+                message = f"Duplicate definition of fragment '{fragment.name}' found in {stored} and {new}."
-                    fragment.name, stored, new)
                 raise GenerationException(message)
 
             dict_to_append_to[fragment.name] = fragment
@@ -573,6 +668,6 @@ class GenerationException(LdGenFailure):
 
     def __str__(self):
         if self.fragment:
-            return "%s\nIn fragment '%s' defined in '%s'." % (self.message, self.fragment.name, self.fragment.path)
+            return f"{self.message}\nIn fragment '{self.fragment.name}' defined in '{self.fragment.path}'."
         else:
             return self.message

tools/ldgen/ldgen/linker_script.py

@@ -24,6 +24,7 @@ class LinkerScript:
 
     MappingMarker = collections.namedtuple('MappingMarker', 'target indent rules')
     ArraysMarker = collections.namedtuple('ArraysMarker', 'target indent rules')
+    MutableMarker = collections.namedtuple('MutableMarker', 'target indent rules')
 
     def __init__(self, template_file):
         self.members = []
@@ -37,16 +38,19 @@ class LinkerScript:
         target = Fragment.IDENTIFIER
         pattern_mapping = White(' \t') + Suppress('mapping') + Suppress('[') + target + Suppress(']')
         pattern_arrays = White(' \t') + Suppress('arrays') + Suppress('[') + target + Suppress(']')
+        pattern_mutable = White(' \t') + Suppress('mutable') + Suppress('[') + target + Suppress(']')
 
         # Find the markers in the template file line by line. If line does not match marker grammar,
         # set it as a literal to be copied as is to the output file.
         for line in lines:
             parsed = False
-            for pattern in (pattern_arrays, pattern_mapping):
+            for pattern in (pattern_arrays, pattern_mapping, pattern_mutable):
                 try:
                     indent, target = pattern.parse_string(line)
                     if pattern is pattern_arrays:
                         marker = LinkerScript.ArraysMarker(target, indent, [])
+                    elif pattern is pattern_mutable:
+                        marker = LinkerScript.MutableMarker(target, indent, [])
                     else:
                         marker = LinkerScript.MappingMarker(target, indent, [])
                     self.members.append(marker)
@@ -65,8 +69,10 @@ class LinkerScript:
 
                 if isinstance(member, self.ArraysMarker):
                     rules = [x for x in mapping_rules[target] if x.tied]
+                elif isinstance(member, self.MutableMarker):
+                    rules = [x for x in mapping_rules[target] if x.mutable and not x.tied]
                 else:
-                    rules = [x for x in mapping_rules[target] if not x.tied]
+                    rules = [x for x in mapping_rules[target] if not x.tied and not x.mutable]
                 member.rules.extend(rules)
             except KeyError:
                 message = GenerationException.UNDEFINED_REFERENCE + " to target '" + target + "'."
@@ -78,7 +84,7 @@ class LinkerScript:
         # Add information that this is a generated file.
         output_file.write('/* Automatically generated file; DO NOT EDIT */\n')
         output_file.write('/* Espressif IoT Development Framework Linker Script */\n')
-        output_file.write('/* Generated from: %s */\n' % self.file)
+        output_file.write(f'/* Generated from: {self.file} */\n')
         output_file.write('\n')
 
         # Do the text replacement

tools/ldgen/ldgen/output_commands.py

@@ -1,5 +1,5 @@
 #
-# SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
+# SPDX-FileCopyrightText: 2021-2025 Espressif Systems (Shanghai) CO LTD
 # SPDX-License-Identifier: Apache-2.0
 #
 from .entity import Entity
@@ -19,16 +19,16 @@ class AlignAtAddress:
     command to be emitted.
     """
 
-    def __init__(self, alignment, tied=False):
+    def __init__(self, alignment, tied=False, mutable=False):
         self.alignment = alignment
         self.tied = tied
+        self.mutable = mutable
 
     def __str__(self):
-        return ('. = ALIGN(%d);' % self.alignment)
+        return f'. = ALIGN({self.alignment});'
 
     def __eq__(self, other):
-        return (isinstance(other, AlignAtAddress) and
+        return isinstance(other, AlignAtAddress) and self.alignment == other.alignment
-                self.alignment == other.alignment)
 
 
 class SymbolAtAddress:
@@ -43,16 +43,16 @@ class SymbolAtAddress:
     an InputSectionDesc.
     """
 
-    def __init__(self, symbol, tied=False):
+    def __init__(self, symbol, tied=False, mutable=False):
         self.symbol = symbol
         self.tied = tied
+        self.mutable = mutable
 
     def __str__(self):
-        return ('%s = ABSOLUTE(.);' % self.symbol)
+        return f'{self.symbol} = ABSOLUTE(.);'
 
     def __eq__(self, other):
-        return (isinstance(other, SymbolAtAddress) and
+        return isinstance(other, SymbolAtAddress) and self.symbol == other.symbol
-                self.symbol == other.symbol)
 
 
 class InputSectionDesc:
@@ -65,7 +65,7 @@ class InputSectionDesc:
     the emitted input section description.
     """
 
-    def __init__(self, entity, sections, exclusions=None, keep=False, sort=None, tied=False):
+    def __init__(self, entity, sections, exclusions=None, keep=False, sort=None, tied=False, mutable=False):
         assert entity.specificity != Entity.Specificity.SYMBOL
 
         self.entity = entity
@@ -74,8 +74,11 @@ class InputSectionDesc:
         self.exclusions = set()
 
         if exclusions:
-            assert not [e for e in exclusions if e.specificity == Entity.Specificity.SYMBOL or
+            assert not [
-                        e.specificity == Entity.Specificity.NONE]
+                e
+                for e in exclusions
+                if e.specificity == Entity.Specificity.SYMBOL or e.specificity == Entity.Specificity.NONE
+            ]
             self.exclusions = set(exclusions)
         else:
             self.exclusions = set()
@@ -83,6 +86,7 @@ class InputSectionDesc:
         self.keep = keep
         self.sort = sort
         self.tied = tied
+        self.mutable = mutable
 
     def __str__(self):
         sections_string = ''
@@ -93,65 +97,67 @@ class InputSectionDesc:
 
             for exc in sorted(self.exclusions):
                 if exc.specificity == Entity.Specificity.ARCHIVE:
-                    exc_string = '*%s' % (exc.archive)
+                    exc_string = f'*{exc.archive}'
                 else:
-                    exc_string = '*%s:%s.*' % (exc.archive, exc.obj)
+                    exc_string = f'*{exc.archive}:{exc.obj}.*'
 
                 exclusion_strings.append(exc_string)
 
             section_strings = []
 
             if exclusion_strings:
-                exclusion_string = 'EXCLUDE_FILE(%s)' % ' '.join(exclusion_strings)
+                exclusion_string = 'EXCLUDE_FILE({})'.format(' '.join(exclusion_strings))
 
                 for section in sorted(self.sections):
-                    section_strings.append('%s %s' % (exclusion_string, section))
+                    section_strings.append(f'{exclusion_string} {section}')
             else:
                 for section in sorted(self.sections):
                     section_strings.append(section)
 
             if self.sort:
                 if self.sort == (None, None):
-                    pattern = 'SORT(%s)'
+                    pattern = 'SORT({})'
                 elif self.sort == ('name', None):
-                    pattern = 'SORT_BY_NAME(%s)'
+                    pattern = 'SORT_BY_NAME({})'
                 elif self.sort == ('alignment', None):
-                    pattern = 'SORT_BY_ALIGNMENT(%s)'
+                    pattern = 'SORT_BY_ALIGNMENT({})'
                 elif self.sort == ('init_priority', None):
-                    pattern = 'SORT_BY_INIT_PRIORITY(%s)'
+                    pattern = 'SORT_BY_INIT_PRIORITY({})'
                 elif self.sort == ('name', 'alignment'):
-                    pattern = 'SORT_BY_NAME(SORT_BY_ALIGNMENT(%s))'
+                    pattern = 'SORT_BY_NAME(SORT_BY_ALIGNMENT({}))'
                 elif self.sort == ('alignment', 'name'):
-                    pattern = 'SORT_BY_ALIGNMENT(SORT_BY_NAME(%s))'
+                    pattern = 'SORT_BY_ALIGNMENT(SORT_BY_NAME({}))'
                 elif self.sort == ('name', 'name'):
-                    pattern = 'SORT_BY_NAME(SORT_BY_NAME(%s))'
+                    pattern = 'SORT_BY_NAME(SORT_BY_NAME({}))'
                 elif self.sort == ('alignment', 'alignment'):
-                    pattern = 'SORT_BY_ALIGNMENT(SORT_BY_ALIGNMENT(%s))'
+                    pattern = 'SORT_BY_ALIGNMENT(SORT_BY_ALIGNMENT({}))'
                 else:
                     raise Exception('Invalid sort arguments')
 
-                section_strings = [(pattern % s) for s in section_strings]
+                section_strings = [pattern.format(s) for s in section_strings]
 
-            sections_string = '(%s)' % ' '.join(section_strings)
+            sections_string = '({})'.format(' '.join(section_strings))
 
         if self.entity.specificity == Entity.Specificity.NONE:
-            entry = '*%s' % (sections_string)
+            entry = f'*{sections_string}'
         elif self.entity.specificity == Entity.Specificity.ARCHIVE:
-            entry = '*%s:%s' % (self.entity.archive, sections_string)
+            entry = f'*{self.entity.archive}:{sections_string}'
         else:
-            entry = '*%s:%s.*%s' % (self.entity.archive, self.entity.obj, sections_string)
+            entry = f'*{self.entity.archive}:{self.entity.obj}.*{sections_string}'
 
         if self.keep:
-            res = 'KEEP(%s)' % entry
+            res = f'KEEP({entry})'
         else:
             res = entry
 
         return res
 
     def __eq__(self, other):
-        return (isinstance(other, InputSectionDesc) and
+        return (
-                self.entity == other.entity and
+            isinstance(other, InputSectionDesc)
-                self.sections == other.sections and
+            and self.entity == other.entity
-                self.exclusions == other.exclusions and
+            and self.sections == other.sections
-                self.keep == other.keep and
+            and self.exclusions == other.exclusions
-                self.sort == other.sort)
+            and self.keep == other.keep
+            and self.sort == other.sort
+        )

tools/ldgen/test/test_generation.py

@@ -12,19 +12,27 @@ import unittest
 from io import StringIO
 
 try:
-    from ldgen.entity import Entity, EntityDB
+    from ldgen.entity import Entity
+    from ldgen.entity import EntityDB
     from ldgen.fragments import parse_fragment_file
-    from ldgen.generation import Generation, GenerationException
+    from ldgen.generation import Generation
+    from ldgen.generation import GenerationException
     from ldgen.linker_script import LinkerScript
-    from ldgen.output_commands import AlignAtAddress, InputSectionDesc, SymbolAtAddress
+    from ldgen.output_commands import AlignAtAddress
+    from ldgen.output_commands import InputSectionDesc
+    from ldgen.output_commands import SymbolAtAddress
     from ldgen.sdkconfig import SDKConfig
 except ImportError:
     sys.path.append(os.path.dirname(os.path.dirname(__file__)))
-    from ldgen.entity import Entity, EntityDB
+    from ldgen.entity import Entity
+    from ldgen.entity import EntityDB
     from ldgen.fragments import parse_fragment_file
-    from ldgen.generation import Generation, GenerationException
+    from ldgen.generation import Generation
+    from ldgen.generation import GenerationException
     from ldgen.linker_script import LinkerScript
-    from ldgen.output_commands import AlignAtAddress, InputSectionDesc, SymbolAtAddress
+    from ldgen.output_commands import AlignAtAddress
+    from ldgen.output_commands import InputSectionDesc
+    from ldgen.output_commands import SymbolAtAddress
     from ldgen.sdkconfig import SDKConfig
 
 ROOT = Entity('*')
@@ -38,7 +46,6 @@ FREERTOS2 = Entity('libfreertos2.a')
 
 
 class GenerationTest(unittest.TestCase):
-
     def setUp(self):
         self.generation = Generation()
         self.entities = None
@@ -121,7 +128,6 @@ class GenerationTest(unittest.TestCase):
 
 
 class DefaultMappingTest(GenerationTest):
-
     def test_rule_generation_default(self):
         # Checks that default rules are generated from
         # the default scheme properly and even if no mappings
@@ -134,7 +140,7 @@ class DefaultMappingTest(GenerationTest):
     def test_default_mapping_lib(self):
         # Mapping a library with default mapping. This should not emit additional rules,
         # other than the default ones.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -146,7 +152,7 @@ entries:
     def test_default_mapping_obj(self):
         # Mapping an object with default mapping. This should not emit additional rules,
         # other than the default ones.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -158,7 +164,7 @@ entries:
     def test_default_mapping_symbol(self):
         # Mapping a symbol with default mapping. This should not emit additional rules,
         # other than the default ones.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -170,7 +176,7 @@ entries:
     def test_default_mapping_all(self):
         # Mapping a library, object, and symbol with default mapping. This should not emit additional rules,
         # other than the default ones.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -187,7 +193,7 @@ entries:
         #
         # This is a check needed to make sure generation does not generate
         # intermediate commands due to presence of symbol mapping.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -203,7 +209,7 @@ entries:
         #
         # This is a check needed to make sure generation does not generate
         # intermediate commands due to presence of symbol mapping.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -214,6 +220,90 @@ entries:
         self.test_rule_generation_default()
 
 
+class MutableMappingTest(GenerationTest):
+    # Collection of tests for mutable library mappings
+
+    def dump_rules(self, rules):
+        # A simple helper for displaying the rules. It can be used to manually
+        # compare the actual and expected rules to identify any issues while
+        # preparing tests.
+        print()
+        for target, section_descs in rules.items():
+            print(f'target: {target}')
+            for section_desc in section_descs:
+                print(f'    {section_desc.entity}: {section_desc.sections}')
+                for exclusion in section_desc.exclusions:
+                    print(f'        {exclusion}')
+
+    def add_mutable_libs_to_rules(self, libs, default_rules):
+        # Insert mutable lib rules and exclusions into default test rules.
+        rules = collections.defaultdict(list)
+        for target, section_descs in default_rules.items():
+            for section_desc in section_descs:
+                # Duplicate the current section description.
+                section_desc_copy = InputSectionDesc(section_desc.entity, section_desc.sections)
+                for lib in libs:
+                    # Exclude each mutable library from ROOT entity rule.
+                    section_desc_copy.exclusions.add(Entity(lib))
+                rules[target].append(section_desc_copy)
+
+            # Add a rule for each mutable library and each ROOT entity rule section.
+            # This is done separately because the order is important.
+            for lib in libs:
+                for section_desc in section_descs:
+                    rules[target].append(InputSectionDesc(Entity(lib), section_desc.sections))
+        return rules
+
+    def test_rule_generation_default(self):
+        # Verifies that the default rules are correctly generated from the
+        # default scheme and that mutable libraries are included in the
+        # generated rules.
+        mutable_libs = ['libmutable.a', 'libmutable2.a']
+
+        self.generation.mutable_libs = mutable_libs
+
+        actual = self.generation.generate(self.entities, False)
+        default_rules = self.generate_default_rules()
+        expected = self.add_mutable_libs_to_rules(mutable_libs, default_rules)
+
+        self.compare_rules(expected, actual)
+        self.generation.mutable_libs = []
+
+    def test_default_mapping_obj(self):
+        # Verifies that libfreertos.a:croutine entity is correctly excluded
+        # from the libfreertos.a entity and moved to iram and dram.
+        mapping = """
+[mapping:test]
+archive: libfreertos.a
+entries:
+    croutine (noflash)
+"""
+        mutable_libs = ['libfreertos.a']
+
+        self.generation.mutable_libs = mutable_libs
+
+        self.add_fragments(mapping)
+        actual = self.generation.generate(self.entities, False)
+        default_rules = self.generate_default_rules()
+        expected = self.add_mutable_libs_to_rules(mutable_libs, default_rules)
+
+        flash_text = expected['flash_text']
+        flash_rodata = expected['flash_rodata']
+        iram0_text = expected['iram0_text']
+        dram0_data = expected['dram0_data']
+
+        # Add exclusions for the libfreertos.a:croutine entity into
+        # libfreertos.a entity in test and rodata.
+        flash_text[1].exclusions.add(CROUTINE)
+        flash_rodata[1].exclusions.add(CROUTINE)
+
+        # Add rules for the libfreertos.a:croutine entity in iram and dram.
+        iram0_text.append(InputSectionDesc(CROUTINE, flash_text[1].sections))
+        dram0_data.append(InputSectionDesc(CROUTINE, flash_rodata[1].sections))
+
+        self.compare_rules(expected, actual)
+
+
 class BasicTest(GenerationTest):
     # Test basic and fundamental interactions between typical
     # entries.
@@ -230,7 +320,7 @@ class BasicTest(GenerationTest):
         # iram0_text
         #   *(.iram ...)
         #   *libfreertos.a(.literal  ...)                                                                          B
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -260,14 +350,14 @@ entries:
         # There should be exclusions in the default commands for flash_text and flash_rodata:
         #
         # flash_text
-        #   *((EXCLUDE_FILE(libfreertos.a:croutine)) .literal ...)                                                          A
+        #   *((EXCLUDE_FILE(libfreertos.a:croutine)) .literal ...)                                           A
         #
         # Commands placing the entire library in iram, dram should be generated:
         #
         # iram0_text
         #   *(.iram ...)
-        #   *libfreertos.a:croutine(.literal  ...)                                                                          B
+        #   *libfreertos.a:croutine(.literal  ...)                                                           B
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -295,19 +385,20 @@ entries:
 
     def test_nondefault_mapping_symbol(self):
         # Test mapping entry different from default for symbol.
-        # There should be exclusions in the default commands for flash_text, as well as the implicit intermediate object command
+        # There should be exclusions in the default commands for flash_text, as
+        # well as the implicit intermediate object command
         # with an exclusion from default:
         #
         # flash_text
-        #   *((EXCLUDE_FILE(libfreertos.a:croutine)) .literal ...)                                                          A
+        #   *((EXCLUDE_FILE(libfreertos.a:croutine)) .literal ...)                                          A
-        #   *libfreertos.a:croutine(.literal  .literal.prvCheckDelayedList ...)                                             B
+        #   *libfreertos.a:croutine(.literal  .literal.prvCheckDelayedList ...)                             B
         #
         # Commands placing the entire library in iram should be generated:
         #
         # iram0_text
         #   *(.iram ...)
-        #   *libfreertos.a:croutine(.text.prvCheckPendingReadyList .literal.prvCheckPendingReadyList)                       C
+        #   *libfreertos.a:croutine(.text.prvCheckPendingReadyList .literal.prvCheckPendingReadyList)       C
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -336,7 +427,9 @@ entries:
         flash_text.append(InputSectionDesc(CROUTINE, set(filtered_sections), []))
 
         # Input section commands in iram_text for #1                                     C
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+        iram0_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         self.compare_rules(expected, actual)
 
@@ -351,14 +444,14 @@ entries:
         # object file, including .debug, .comment and other input section.
         #
         # flash.rodata
-        #   *((EXCLUDE_FILE(*libsoc.a:temperature_sensor_periph.*)) .rodata.* ...)                                          A
+        #   *((EXCLUDE_FILE(*libsoc.a:temperature_sensor_periph.*)) .rodata.* ...)                          A
-        #   # *libsoc.a:temperature_sensor_periph.*                                                                         X
+        #   # *libsoc.a:temperature_sensor_periph.*                                                         X
         #
         # Commands placing the entire library in iram should be generated:
         #
         # dram0_data
-        #   *libsoc.a:temperature_sensor_periph.*(.rodata.temperature_sensor_attribute)                                     B
+        #   *libsoc.a:temperature_sensor_periph.*(.rodata.temperature_sensor_attribute)                     B
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libsoc.a
 entries:
@@ -376,14 +469,15 @@ entries:
         flash_rodata[0].exclusions.add(TEMPERATURE_SENSOR_PERIPH)
 
         # Input section commands in dram0_data for #1                                    B
-        dram0_data.append(InputSectionDesc(TEMPERATURE_SENSOR_PERIPH,
+        dram0_data.append(
-                                           set(['.rodata.temperature_sensor_attributes']),
+            InputSectionDesc(TEMPERATURE_SENSOR_PERIPH, set(['.rodata.temperature_sensor_attributes']), [])
-                                           []))
+        )
 
         self.compare_rules(expected, actual)
 
     def test_default_symbol_nondefault_lib(self):
-        # Test default symbol mapping with different lib mapping. This should create an implicit intermediate object command.
+        # Test default symbol mapping with different lib mapping. This should
+        # create an implicit intermediate object command.
         # The significant targets are flash_text, flash_rodata, iram0_text, dram0_data.
         #
         # flash_text
@@ -403,7 +497,7 @@ entries:
         #  libfreertos.a ( .rodata ...)                                                                     C.2
         #
         # Only default commands are in the other targets.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -440,7 +534,9 @@ entries:
         iram0_text.append(InputSectionDesc(CROUTINE, set(filtered_sections), []))
 
         # Command for #2                                                                                    B
-        flash_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+        flash_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         self.compare_rules(expected, actual)
 
@@ -465,7 +561,7 @@ entries:
         #   *libfreertos.a:croutine(.rodata ....)                                                                    C.2
         #
         # Only default commands are in the other targets
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -499,7 +595,9 @@ entries:
         dram0_data.append(InputSectionDesc(CROUTINE, flash_rodata[0].sections, []))
 
         # Command for #2                                                                                    B
-        flash_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+        flash_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         self.compare_rules(expected, actual)
 
@@ -532,7 +630,7 @@ entries:
         #  libfreertos.a (EXCLUDE_FILE(libfreertos:croutine) .rodata ...)                                    C
         #
         # For the other targets only the default commands should be present.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -575,14 +673,16 @@ entries:
         flash_text.append(InputSectionDesc(CROUTINE, set(filtered_sections), []))
 
         # Command for #3                                                                                    D
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+        iram0_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         self.compare_rules(expected, actual)
 
     def test_nondefault_but_same_lib_and_obj(self):
         # Extension of DefaultMappingTest. Commands should not be generated for #2, since it does similar mapping
         # to #1. Output is similar to test_different_mapping_lib.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -594,7 +694,7 @@ entries:
     def test_nondefault_but_same_lib_and_sym(self):
         # Extension of DefaultMappingTest. Commands should not be generated for #2, since it does similar mapping
         # to #1. Output is similar to test_different_mapping_lib.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -606,7 +706,7 @@ entries:
     def test_nondefault_but_same_obj_and_sym(self):
         # Commands should not be generated for #2, since it does similar mapping
         # to #1. Output is similar to test_different_mapping_obj.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -627,7 +727,7 @@ entries:
         # iram0_text
         #
         #
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -659,8 +759,12 @@ entries:
         flash_text.append(InputSectionDesc(CROUTINE, set(filtered_sections), []))
 
         # Commands for #1 & 2
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckDelayedList', '.literal.prvCheckDelayedList']), []))
+        iram0_text.append(
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckDelayedList', '.literal.prvCheckDelayedList']), [])
+        )
+        iram0_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         self.compare_rules(expected, actual)
 
@@ -671,7 +775,7 @@ entries:
         # iram0_text
         #   * (.custom_section)                                  A
         #   * (.iram .iram.*)
-        mapping = u"""
+        mapping = """
 [sections:custom_section]
 entries:
     .custom_section
@@ -700,7 +804,6 @@ entries:
 
 
 class AdvancedTest(GenerationTest):
-
     # Test valid but quirky cases, corner cases, failure cases, and
     # cases involving interaction between schemes, other mapping
     # fragments.
@@ -727,7 +830,7 @@ class AdvancedTest(GenerationTest):
         #   *(.data ..)
         #   *(.dram ...)
         #   *libfreertos.a:croutine(.rodata .rodata.*)                                                               D
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -768,20 +871,20 @@ entries:
         # This operation should succeed with the following commands:
         #
         # flash_text
-        #   *(EXCLUDE_FILE(libfreertos.a:croutine) .text ...)                                                        A
+        #   *(EXCLUDE_FILE(libfreertos.a:croutine) .text ...)                                                A
         #
         # flash_rodata
-        #   *(EXCLUDE_FILE(libfreertos.a:croutine) .rodata ...)                                                      B
+        #   *(EXCLUDE_FILE(libfreertos.a:croutine) .rodata ...)                                              B
         #
         # iram0_text
         #   *(.iram ...)
-        #   *libfreertos.a:croutine(.text .text.* ...)                                                               C
+        #   *libfreertos.a:croutine(.text .text.* ...)                                                       C
         #
         # dram0_data
         #   *(.data ..)
         #   *(.dram ...)
-        #   *libfreertos.a:croutine(.rodata .rodata.*)                                                               D
+        #   *libfreertos.a:croutine(.rodata .rodata.*)                                                       D
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -818,7 +921,7 @@ entries:
         # noflash = text -> iram0_text, rodata -> dram0_data
         #
         # This operation should fail.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -837,7 +940,7 @@ entries:
         # noflash = .text -> iram0_text, .rodata -> dram0_data
         #
         # This operation should fail.
-        mapping = u"""
+        mapping = """
 [sections:custom_text]
 entries:
     .text+
@@ -861,42 +964,42 @@ entries:
         # using another. Another object and symbol is mapped the other way around.
         #
         # flash_text
-        #   *(EXCLUDE_FILE(libfreertos.a:croutine libfreertos.a:timers) .text ...)                                                        A, B
+        #   *(EXCLUDE_FILE(libfreertos.a:croutine libfreertos.a:timers) .text ...)                           A, B
         #
         # flash_rodata
-        #   *(EXCLUDE_FILE(libfreertos.a:croutine libfreertos.a:timers) .rodata ...)                                                      A, B
+        #   *(EXCLUDE_FILE(libfreertos.a:croutine libfreertos.a:timers) .rodata ...)                         A, B
         #
         # dram0_data
-        #   *(EXCLUDE_FILES(libfreertos.a:timers) .data ..)                                                                               B
+        #   *(EXCLUDE_FILES(libfreertos.a:timers) .data ..)                                                  B
         #   *(.dram ...)
-        #   *libfreertos.a:croutine(.rodata .rodata.*)                                                                                    C
+        #   *libfreertos.a:croutine(.rodata .rodata.*)                                                       C
-        #   *libfreertos.a:timers(.rodata.prvProcessReceivedCommands ...)                                                                 E
+        #   *libfreertos.a:timers(.rodata.prvProcessReceivedCommands ...)                                    E
         #
         # dram0_bss
-        #   *(EXCLUDE_FILE(libfreertos.a:timers) .bss .bss.* ...)                                                                         B
+        #   *(EXCLUDE_FILE(libfreertos.a:timers) .bss .bss.* ...)                                            B
-        #   *(EXCLUDE_FILE(libfreertos.a:timers) COMMON)                                                                                  B
+        #   *(EXCLUDE_FILE(libfreertos.a:timers) COMMON)                                                     B
         #
         # iram0_text
         #   *(.iram ...)
-        #   *libfreertos.a:croutine(.literal  .literal.prvCheckDelayedList ...)                                                           C
+        #   *libfreertos.a:croutine(.literal  .literal.prvCheckDelayedList ...)                              C
-        #   *libfreertos.a:timers(.literal  .literal.prvProcessReceivedCommands ...)                                                      E
+        #   *libfreertos.a:timers(.literal  .literal.prvProcessReceivedCommands ...)                         E
         #
         # rtc_text
         #   *(rtc.text .rtc.literal)
-        #   libfreertos.a:croutine (.text.prvCheckPendingReadyList .literal.prvCheckPendingReadyList)                                     F
+        #   libfreertos.a:croutine (.text.prvCheckPendingReadyList .literal.prvCheckPendingReadyList)        F
-        #   libfreertos.a:timers (.text .text.prvCheckForValidListAndQueue ...)                                                           D.2
+        #   libfreertos.a:timers (.text .text.prvCheckForValidListAndQueue ...)                              D.2
         #
         # rtc_data
         #   *(rtc.data)
         #   *(rtc.rodata)
-        #   libfreertos.a:timers (.data .data.*)                                                                                          D
+        #   libfreertos.a:timers (.data .data.*)                                                             D
-        #   libfreertos.a:timers (.rodata ...)                                                                                            D.2
+        #   libfreertos.a:timers (.rodata ...)                                                               D.2
         #
         # rtc_bss
         #   *(rtc.bss .rtc.bss)
-        #   libfreertos.a:timers (.bss .bss.*)                                                                                            D
+        #   libfreertos.a:timers (.bss .bss.*)                                                               D
-        #   libfreertos.a:timers (COMMON)                                                                                                 D
+        #   libfreertos.a:timers (COMMON)                                                                    D
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -944,7 +1047,9 @@ entries:
 
         # Commands for #4                                                                   F
         # Processed first due to alphabetical ordering
-        rtc_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+        rtc_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         # Commands for #2                                                                   D
         # List all relevant sections excluding #3 for text -> rtc_text and                  D.2
@@ -966,7 +1071,11 @@ entries:
         rtc_bss.append(InputSectionDesc(TIMERS, dram0_bss[1].sections, []))
 
         # Commands for #3                                                                  E
-        iram0_text.append(InputSectionDesc(TIMERS, set(['.text.prvProcessReceivedCommands', '.literal.prvProcessReceivedCommands']), []))
+        iram0_text.append(
+            InputSectionDesc(
+                TIMERS, set(['.text.prvProcessReceivedCommands', '.literal.prvProcessReceivedCommands']), []
+            )
+        )
         dram0_data.append(InputSectionDesc(TIMERS, set(['.rodata.prvProcessReceivedCommands']), []))
 
         self.compare_rules(expected, actual)
@@ -983,7 +1092,7 @@ entries:
         #   * (EXCLUDE_FILE(libfreertos.a libfreertos.a:croutine) .text ...)
         #
         # iram0_text
-        mapping = u"""
+        mapping = """
 [mapping:test_1]
 archive: libfreertos.a
 entries:
@@ -1028,7 +1137,7 @@ entries:
         #
         # Uses the same entries as C_05 but spreads them across
         # two fragments. The output should still be the same.
-        mapping = u"""
+        mapping = """
 [mapping:test_1]
 archive: libfreertos.a
 entries:
@@ -1046,7 +1155,7 @@ entries:
     def test_mapping_same_lib_in_multiple_fragments_conflict(self):
         # Test mapping fragments operating on the same archive
         # with conflicting mappings.
-        mapping = u"""
+        mapping = """
 [mapping:test_1]
 archive: libfreertos.a
 entries:
@@ -1078,7 +1187,7 @@ entries:
         #   libfreertos:croutine(.text.prvCheckPendingReadyList .literal.prvCheckPendingReadyList)              G
         #   libfreertos2:croutine(.text .literal ...)                                                           D
         #   libfreertos2:croutine2(.text .literal ...)                                                          E
-        mapping = u"""
+        mapping = """
 [mapping:freertos2]
 archive: libfreertos2.a
 entries:
@@ -1116,8 +1225,12 @@ entries:
         flash_text.append(InputSectionDesc(CROUTINE, set(filtered_sections), []))
 
         # Command for
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckDelayedList', '.literal.prvCheckDelayedList']), []))
+        iram0_text.append(
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckDelayedList', '.literal.prvCheckDelayedList']), [])
+        )
+        iram0_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         iram0_text.append(InputSectionDesc(Entity(FREERTOS2.archive, 'croutine'), flash_text[0].sections, []))
         iram0_text.append(InputSectionDesc(Entity(FREERTOS2.archive, 'croutine2'), flash_text[0].sections, []))
@@ -1126,7 +1239,7 @@ entries:
 
     def test_ambigious_obj(self):
         # Command generation for ambiguous entry should fail.
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -1143,7 +1256,7 @@ entries:
         #
         # 'custom_scheme' entries conflict the 'default' scheme
         # entries.
-        mapping = u"""
+        mapping = """
 [scheme:custom_scheme]
 entries:
     flash_text -> iram0_text
@@ -1163,7 +1276,7 @@ entries:
         #
         # custom_scheme has the 'iram -> iram0_text' in common with
         # default scheme
-        mapping = u"""
+        mapping = """
 [sections:custom_section]
 entries:
     .custom_section
@@ -1198,7 +1311,7 @@ class ConfigTest(GenerationTest):
     def _test_conditional_on_scheme(self, perf, alt=None):
         # Test that proper commands are generated if using
         # schemes with conditional entries.
-        scheme = u"""
+        scheme = """
 [sections:cond_text_data]
 entries:
     if PERFORMANCE_LEVEL >= 1:
@@ -1215,7 +1328,7 @@ entries:
         cond_text_data -> dram0_data
 """
 
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: lib.a
 entries:
@@ -1250,7 +1363,7 @@ entries:
     def test_conditional_mapping(self, alt=None):
         # Test that proper commands are generated
         # in conditional mapping entries.
-        mapping = u"""
+        mapping = """
 [mapping:default]
 archive: *
 entries:
@@ -1299,7 +1412,7 @@ entries:
     def test_multiple_fragment_same_lib_conditional(self):
         # Test conditional entries on new mapping fragment grammar.
         # across multiple fragments.
-        mapping = u"""
+        mapping = """
 [mapping:default]
 archive: *
 entries:
@@ -1331,7 +1444,6 @@ entries:
 
 
 class FlagTest(GenerationTest):
-
     # Test correct generation of mapping fragment entries
     # with flags.
 
@@ -1362,7 +1474,7 @@ class FlagTest(GenerationTest):
         #   libfreertos.a:croutine(.text .literal ...)                                  I
         #   . = ALIGN(4)                                                                G.2
         #   _sym1_end                                                                   H.2
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -1422,7 +1534,7 @@ entries:
         # iram0_text
         #   *(.iram .iram.*)
         #   libfreertos.a:croutine(.text.prvCheckPendingReadyList ...)                  D
-        mapping = u"""
+        mapping = """
 [mapping:default]
 archive: *
 entries:
@@ -1466,7 +1578,9 @@ entries:
         flash_text.append(SymbolAtAddress('_sym1_end'))
 
         # Command for #3                                               D
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+        iram0_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         self.compare_rules(expected, actual)
 
@@ -1484,7 +1598,7 @@ entries:
         # iram0_text
         #   *(.iram .iram.*)
         #   libfreertos.a:croutine(.text.prvCheckPendingReadyList ...)                  D
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -1523,7 +1637,9 @@ entries:
         flash_text.append(SymbolAtAddress('_sym1_end'))
 
         # Command for #3                                               C
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+        iram0_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         self.compare_rules(expected, actual)
 
@@ -1540,7 +1656,7 @@ entries:
         # iram0_text
         #   *(.iram .iram.*)
         #   libfreertos.a:croutine(.text.prvCheckPendingReadyList ...)                  C
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -1575,7 +1691,9 @@ entries:
         flash_text.append(SymbolAtAddress('_sym1_end'))
 
         # Command for #3                                               C
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+        iram0_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         self.compare_rules(expected, actual)
 
@@ -1591,7 +1709,7 @@ entries:
         # iram0_text
         #   *(.iram .iram.*)
         #   libfreertos.a:croutine(.text.prvCheckPendingReadyList ...)                  D
-        mapping = u"""
+        mapping = """
 [mapping:default]
 archive: *
 entries:
@@ -1636,7 +1754,9 @@ entries:
         flash_text.append(InputSectionDesc(CROUTINE, set(filtered_sections), []))
 
         # Command for #4                                               D
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+        iram0_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         self.compare_rules(expected, actual)
 
@@ -1653,7 +1773,7 @@ entries:
         # iram0_text
         #   *(.iram .iram.*)
         #   libfreertos.a:croutine(.text.prvCheckPendingReadyList ...)                  D
-        mapping = u"""
+        mapping = """
 [mapping:test]
 archive: libfreertos.a
 entries:
@@ -1693,14 +1813,16 @@ entries:
         flash_text.append(InputSectionDesc(CROUTINE, set(filtered_sections), []))
 
         # Command for #3                                               C
-        iram0_text.append(InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), []))
+        iram0_text.append(
+            InputSectionDesc(CROUTINE, set(['.text.prvCheckPendingReadyList', '.literal.prvCheckPendingReadyList']), [])
+        )
 
         self.compare_rules(expected, actual)
 
     def test_flag_additions(self):
         # Test ability to add flags as long as no other mapping fragments
         # does the same thing.
-        mapping = u"""
+        mapping = """
 [mapping:default_add_flag]
 archive: *
 entries:
@@ -1721,7 +1843,7 @@ entries:
     def test_flags_flag_additions_duplicate(self):
         # Test same flags added to same entity - these
         # are ignored.
-        mapping = u"""
+        mapping = """
 [mapping:default_add_flag_1]
 archive: *
 entries:
@@ -1748,7 +1870,7 @@ entries:
     def test_flags_flag_additions_conflict(self):
         # Test condition where multiple fragments specifies flags
         # to same entity - should generate exception.
-        mapping = u"""
+        mapping = """
 [mapping:default_add_flag_1]
 archive: *
 entries: