esp-idf/components/esp_system/ld/esp32c3/sections.ld.in

/* Default entry point */
ENTRY(call_start_cpu0);

SECTIONS
{
  /**
   * RTC fast memory holds RTC wake stub code,
   * including from any source file named rtc_wake_stub*.c
   */
  .rtc.text :
  {
    . = ALIGN(4);

    mapping[rtc_text]

    *rtc_wake_stub*.*(.literal .text .literal.* .text.*)
    _rtc_text_end = ABSOLUTE(.);
  } > rtc_iram_seg

  /**
   * This section is required to skip rtc.text area because rtc_iram_seg and
   * rtc_data_seg are reflect the same address space on different buses.
   */
  .rtc.dummy :
  {
    _rtc_dummy_start = ABSOLUTE(.);
    _rtc_fast_start = ABSOLUTE(.);
    . = SIZEOF(.rtc.text);
    _rtc_dummy_end = ABSOLUTE(.);
  } > rtc_data_seg

  /**
   * This section located in RTC FAST Memory area.
   * It holds data marked with RTC_FAST_ATTR attribute.
   * See the file "esp_attr.h" for more information.
   */
  .rtc.force_fast :
  {
    . = ALIGN(4);
    _rtc_force_fast_start = ABSOLUTE(.);

    mapping[rtc_force_fast]

    *(.rtc.force_fast .rtc.force_fast.*)
    . = ALIGN(4) ;
    _rtc_force_fast_end = ABSOLUTE(.);
  } > rtc_data_seg

  /**
   * RTC data section holds RTC wake stub
   * data/rodata, including from any source file
   * named rtc_wake_stub*.c and the data marked with
   * RTC_DATA_ATTR, RTC_RODATA_ATTR attributes.
   */
  .rtc.data :
  {
    _rtc_data_start = ABSOLUTE(.);

    mapping[rtc_data]

    *rtc_wake_stub*.*(.data .rodata .data.* .rodata.* .bss .bss.*)
    _rtc_data_end = ABSOLUTE(.);
  } > rtc_data_location

  /* RTC bss, from any source file named rtc_wake_stub*.c */
  .rtc.bss (NOLOAD) :
  {
    _rtc_bss_start = ABSOLUTE(.);
    *rtc_wake_stub*.*(.bss .bss.*)
    *rtc_wake_stub*.*(COMMON)

    mapping[rtc_bss]

    _rtc_bss_end = ABSOLUTE(.);
  } > rtc_data_location

  /**
   * This section holds data that should not be initialized at power up
   * and will be retained during deep sleep.
   * User data marked with RTC_NOINIT_ATTR will be placed
   * into this section. See the file "esp_attr.h" for more information.
   */
  .rtc_noinit (NOLOAD):
  {
    . = ALIGN(4);
    _rtc_noinit_start = ABSOLUTE(.);
    *(.rtc_noinit .rtc_noinit.*)
    . = ALIGN(4) ;
    _rtc_noinit_end = ABSOLUTE(.);
  } > rtc_data_location

  /**
   * This section located in RTC SLOW Memory area.
   * It holds data marked with RTC_SLOW_ATTR attribute.
   * See the file "esp_attr.h" for more information.
   */
  .rtc.force_slow :
  {
    . = ALIGN(4);
    _rtc_force_slow_start = ABSOLUTE(.);
    *(.rtc.force_slow .rtc.force_slow.*)
    . = ALIGN(4) ;
    _rtc_force_slow_end = ABSOLUTE(.);
  } > rtc_slow_seg

  /* Get size of rtc slow data based on rtc_data_location alias */
  _rtc_slow_length = (ORIGIN(rtc_slow_seg) == ORIGIN(rtc_data_location))
                        ? (_rtc_force_slow_end - _rtc_data_start)
                        : (_rtc_force_slow_end - _rtc_force_slow_start);

  _rtc_fast_length = (ORIGIN(rtc_slow_seg) == ORIGIN(rtc_data_location))
                        ? (_rtc_force_fast_end - _rtc_fast_start)
                        : (_rtc_noinit_end - _rtc_fast_start);

  ASSERT((_rtc_slow_length <= LENGTH(rtc_slow_seg)),
          "RTC_SLOW segment data does not fit.")

  ASSERT((_rtc_fast_length <= LENGTH(rtc_data_seg)),
          "RTC_FAST segment data does not fit.")

  .iram0.text :
  {
    _iram_start = ABSOLUTE(.);
    /* Vectors go to start of IRAM */
    ASSERT(ABSOLUTE(.) % 0x100 == 0, "vector address must be 256 byte aligned");
    KEEP(*(.exception_vectors.text));
    . = ALIGN(4);

    _invalid_pc_placeholder = ABSOLUTE(.);

    /* Code marked as running out of IRAM */
    _iram_text_start = ABSOLUTE(.);

    mapping[iram0_text]

  } > iram0_0_seg

  /**
   * This section is required to skip .iram0.text area because iram0_0_seg and
   * dram0_0_seg reflect the same address space on different buses.
   */
  .dram0.dummy (NOLOAD):
  {
    . = ORIGIN(dram0_0_seg) + _iram_end - _iram_start;
  } > dram0_0_seg

  .dram0.data :
  {
    _data_start = ABSOLUTE(.);
    *(.gnu.linkonce.d.*)
    *(.data1)
    __global_pointer$ = . + 0x800;
    *(.sdata)
    *(.sdata.*)
    *(.gnu.linkonce.s.*)
    *(.sdata2)
    *(.sdata2.*)
    *(.gnu.linkonce.s2.*)
    *(.jcr)

    _esp_system_init_fn_array_start = ABSOLUTE(.);
    KEEP (*(SORT(.esp_system_init_fn) SORT(.esp_system_init_fn.*)))
    _esp_system_init_fn_array_end = ABSOLUTE(.);

    mapping[dram0_data]

    _data_end = ABSOLUTE(.);
    . = ALIGN(4);
  } > dram0_0_seg

  /**
   * This section holds data that should not be initialized at power up.
   * The section located in Internal SRAM memory region. The macro _NOINIT
   * can be used as attribute to place data into this section.
   * See the "esp_attr.h" file for more information.
   */
  .noinit (NOLOAD):
  {
    . = ALIGN(4);
    _noinit_start = ABSOLUTE(.);
    *(.noinit .noinit.*)
    . = ALIGN(4) ;
    _noinit_end = ABSOLUTE(.);
  } > dram0_0_seg

  /* Shared RAM */
  .dram0.bss (NOLOAD) :
  {
    . = ALIGN (8);
    _bss_start = ABSOLUTE(.);

    mapping[dram0_bss]

    *(.dynsbss)
    *(.sbss)
    *(.sbss.*)
    *(.gnu.linkonce.sb.*)
    *(.scommon)
    *(.sbss2)
    *(.sbss2.*)
    *(.gnu.linkonce.sb2.*)
    *(.dynbss)
    *(.share.mem)
    *(.gnu.linkonce.b.*)

    . = ALIGN (8);
    _bss_end = ABSOLUTE(.);
  } > dram0_0_seg

  ASSERT(((_bss_end - ORIGIN(dram0_0_seg)) <= LENGTH(dram0_0_seg)), "DRAM segment data does not fit.")

  .flash.text :
  {
    _stext = .;
    _instruction_reserved_start = ABSOLUTE(.);
    _text_start = ABSOLUTE(.);

    mapping[flash_text]

    *(.stub .gnu.warning .gnu.linkonce.literal.* .gnu.linkonce.t.*.literal .gnu.linkonce.t.*)
    *(.irom0.text) /* catch stray ICACHE_RODATA_ATTR */
    *(.fini.literal)
    *(.fini)
    *(.gnu.version)

    /** CPU will try to prefetch up to 16 bytes of
      * of instructions. This means that any configuration (e.g. MMU, PMS) must allow
      * safe access to up to 16 bytes after the last real instruction, add
      * dummy bytes to ensure this
      */
    . += 16;

    _text_end = ABSOLUTE(.);
    _instruction_reserved_end = ABSOLUTE(.);
    _etext = .;

    /**
     * Similar to _iram_start, this symbol goes here so it is
     * resolved by addr2line in preference to the first symbol in
     * the flash.text segment.
     */
    _flash_cache_start = ABSOLUTE(0);
  } > default_code_seg

  /**
   * This dummy section represents the .flash.text section but in default_rodata_seg.
   * Thus, it must have its alignement and (at least) its size.
   */
  .flash_rodata_dummy (NOLOAD):
  {
    _flash_rodata_dummy_start = .;
    /* Start at the same alignement constraint than .flash.text */
    . = ALIGN(ALIGNOF(.flash.text));
    /* Create an empty gap as big as .flash.text section */
    . = . + SIZEOF(.flash.text);
    /* Prepare the alignement of the section above. Few bytes (0x20) must be
     * added for the mapping header. */
    . = ALIGN(0x10000) + 0x20;
    _rodata_reserved_start = .;
  } > default_rodata_seg

  .flash.appdesc : ALIGN(0x10)
  {
    _rodata_start = ABSOLUTE(.);

    *(.rodata_desc .rodata_desc.*)               /* Should be the first.  App version info.        DO NOT PUT ANYTHING BEFORE IT! */
    *(.rodata_custom_desc .rodata_custom_desc.*) /* Should be the second. Custom app version info. DO NOT PUT ANYTHING BEFORE IT! */

    /* Create an empty gap within this section. Thanks to this, the end of this
     * section will match .flash.rodata's begin address. Thus, both sections
     * will be merged when creating the final bin image. */
    . = ALIGN(ALIGNOF(.flash.rodata));
  } >default_rodata_seg

  .flash.rodata : ALIGN(0x10)
  {
    _flash_rodata_start = ABSOLUTE(.);

    mapping[flash_rodata]

    *(.irom1.text) /* catch stray ICACHE_RODATA_ATTR */
    *(.gnu.linkonce.r.*)
    *(.rodata1)
    __XT_EXCEPTION_TABLE_ = ABSOLUTE(.);
    *(.xt_except_table)
    *(.gcc_except_table .gcc_except_table.*)
    *(.gnu.linkonce.e.*)
    *(.gnu.version_r)
    . = (. + 7) & ~ 3;
    /*
     * C++ constructor and destructor tables
     * Don't include anything from crtbegin.o or crtend.o, as IDF doesn't use toolchain crt.
     *
     * RISC-V gcc is configured with --enable-initfini-array so it emits an .init_array section instead.
     * But the init_priority sections will be sorted for iteration in ascending order during startup.
     * The rest of the init_array sections is sorted for iteration in descending order during startup, however.
     * Hence a different section is generated for the init_priority functions which is iterated in
     * ascending order during startup. The corresponding code can be found in startup.c.
     */
    __init_priority_array_start = ABSOLUTE(.);
    KEEP (*(EXCLUDE_FILE (*crtend.* *crtbegin.*) .init_array.*))
    __init_priority_array_end = ABSOLUTE(.);
    __init_array_start = ABSOLUTE(.);
    KEEP (*(EXCLUDE_FILE (*crtend.* *crtbegin.*) .init_array))
    __init_array_end = ABSOLUTE(.);
    KEEP (*crtbegin.*(.dtors))
    KEEP (*(EXCLUDE_FILE (*crtend.*) .dtors))
    KEEP (*(SORT(.dtors.*)))
    KEEP (*(.dtors))
    /* C++ exception handlers table: */
    __XT_EXCEPTION_DESCS_ = ABSOLUTE(.);
    *(.xt_except_desc)
    *(.gnu.linkonce.h.*)
    __XT_EXCEPTION_DESCS_END__ = ABSOLUTE(.);
    *(.xt_except_desc_end)
    *(.dynamic)
    *(.gnu.version_d)
    /* Addresses of memory regions reserved via SOC_RESERVE_MEMORY_REGION() */
    soc_reserved_memory_region_start = ABSOLUTE(.);
    KEEP (*(.reserved_memory_address))
    soc_reserved_memory_region_end = ABSOLUTE(.);
    _rodata_end = ABSOLUTE(.);
    /* Literals are also RO data. */
    _lit4_start = ABSOLUTE(.);
    *(*.lit4)
    *(.lit4.*)
    *(.gnu.linkonce.lit4.*)
    _lit4_end = ABSOLUTE(.);
    . = ALIGN(4);
    _thread_local_start = ABSOLUTE(.);
    *(.tdata)
    *(.tdata.*)
    *(.tbss)
    *(.tbss.*)
    *(.srodata)
    *(.srodata.*)
    _thread_local_end = ABSOLUTE(.);
    _rodata_reserved_end = ABSOLUTE(.);
    . = ALIGN(ALIGNOF(.eh_frame));
  } > default_rodata_seg

  /* Keep this section shall be at least aligned on 4 */
  .eh_frame : ALIGN(8)
  {
    __eh_frame = ABSOLUTE(.);
    KEEP (*(.eh_frame))
    __eh_frame_end = ABSOLUTE(.);
    /* Guarantee that this section and the next one will be merged by making
     * them adjacent. */
    . = ALIGN(ALIGNOF(.eh_frame_hdr));
  } > default_rodata_seg

  /* To avoid any exception in C++ exception frame unwinding code, this section
   * shall be aligned on 8. */
  .eh_frame_hdr : ALIGN(8)
  {
    __eh_frame_hdr = ABSOLUTE(.);
    KEEP (*(.eh_frame_hdr))
    __eh_frame_hdr_end = ABSOLUTE(.);
  } > default_rodata_seg

  .flash.rodata_noload (NOLOAD) :
  {
    . = ALIGN (4);
    mapping[rodata_noload]
  } > default_rodata_seg

  /* Marks the end of IRAM code segment */
  .iram0.text_end (NOLOAD) :
  {
    /* C3 memprot requires 512 B alignment for split lines */
    . = ALIGN (0x200);
    /* iram_end_test section exists for use by memprot unit tests only */
    *(.iram_end_test)
    _iram_text_end = ABSOLUTE(.);
  } > iram0_0_seg

  .iram0.data :
  {
    . = ALIGN(16);
    _iram_data_start = ABSOLUTE(.);

    mapping[iram0_data]

    _iram_data_end = ABSOLUTE(.);
  } > iram0_0_seg

  .iram0.bss (NOLOAD) :
  {
    . = ALIGN(16);
    _iram_bss_start = ABSOLUTE(.);

    mapping[iram0_bss]

    _iram_bss_end = ABSOLUTE(.);
    . = ALIGN(16);
    _iram_end = ABSOLUTE(.);
  } > iram0_0_seg

  /* Marks the end of data, bss and possibly rodata  */
  .dram0.heap_start (NOLOAD) :
  {
    . = ALIGN (16);
    _heap_start = ABSOLUTE(.);
  } > dram0_0_seg
}

ASSERT(((_iram_end - ORIGIN(iram0_0_seg)) <= LENGTH(iram0_0_seg)),
          "IRAM0 segment data does not fit.")

ASSERT(((_heap_start - ORIGIN(dram0_0_seg)) <= LENGTH(dram0_0_seg)),
          "DRAM segment data does not fit.")