esp-idf/components/esp_system/ld/esp32/sections.ld.in

/*
 * SPDX-FileCopyrightText: 2021 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */
/*  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.
     The memory location of the data is dependent on
     CONFIG_ESP32_RTCDATA_IN_FAST_MEM option.
  */
  .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.
	 The memory location of the data is dependent on
     CONFIG_ESP32_RTCDATA_IN_FAST_MEM option.
  */
  .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.")

  /* Send .iram0 code to iram */
  .iram0.vectors :
  {
    _iram_start = ABSOLUTE(.);
    /* Vectors go to IRAM */
    _vector_table = ABSOLUTE(.);
    /* Vectors according to builds/RF-2015.2-win32/esp108_v1_2_s5_512int_2/config.html */
    . = 0x0;
    KEEP(*(.WindowVectors.text));
    . = 0x180;
    KEEP(*(.Level2InterruptVector.text));
    . = 0x1c0;
    KEEP(*(.Level3InterruptVector.text));
    . = 0x200;
    KEEP(*(.Level4InterruptVector.text));
    . = 0x240;
    KEEP(*(.Level5InterruptVector.text));
    . = 0x280;
    KEEP(*(.DebugExceptionVector.text));
    . = 0x2c0;
    KEEP(*(.NMIExceptionVector.text));
    . = 0x300;
    KEEP(*(.KernelExceptionVector.text));
    . = 0x340;
    KEEP(*(.UserExceptionVector.text));
    . = 0x3C0;
    KEEP(*(.DoubleExceptionVector.text));
    . = 0x400;
    _invalid_pc_placeholder = ABSOLUTE(.);
    *(.*Vector.literal)

    *(.UserEnter.literal);
    *(.UserEnter.text);
    . = ALIGN (16);
    *(.entry.text)
    *(.init.literal)
    *(.init)

    _init_end = ABSOLUTE(.);
  } > iram0_0_seg

  .iram0.text :
  {
    /* Code marked as runnning out of IRAM */
    _iram_text_start = ABSOLUTE(.);

    mapping[iram0_text]

  } > iram0_0_seg

  .dram0.data :
  {
    _data_start = ABSOLUTE(.);
    *(.gnu.linkonce.d.*)
    *(.data1)
    *(.sdata)
    *(.sdata.*)
    *(.gnu.linkonce.s.*)
    *(.gnu.linkonce.s2.*)
    *(.jcr)

    mapping[dram0_data]

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

  /**
   * This section holds data that won't be initialised when startup.
   * This section locates in External RAM region.
   */
  .ext_ram_noinit (NOLOAD) :
  {
    _ext_ram_noinit_start = ABSOLUTE(.);
    *(.ext_ram_noinit*)
    . = ALIGN(4);
    _ext_ram_noinit_end = ABSOLUTE(.);
  } > extern_ram_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

   /* external memory bss, from any global variable with EXT_RAM_BSS_ATTR attribute*/
  .ext_ram.bss (NOLOAD) :
  {
    _ext_ram_bss_start = ABSOLUTE(.);

    mapping[extern_ram]

    . = ALIGN(4);
    _ext_ram_bss_end = ABSOLUTE(.);
  } > extern_ram_seg

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

    mapping[dram0_bss]

    . = 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.appdesc : ALIGN(0x10)
  {
    _rodata_reserved_start = ABSOLUTE(.);  /* This is a symbol marking the flash.rodata start, this can be used for mmu driver to maintain virtual address */
    _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 .flah.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)
    . = (. + 3) & ~ 3;
    __eh_frame = ABSOLUTE(.);
    KEEP(*(.eh_frame))
    . = (. + 7) & ~ 3;
    /*  C++ constructor and destructor tables

        Make a point of not including anything from crtbegin.o or crtend.o, as IDF doesn't use toolchain crt
      */
    __init_array_start = ABSOLUTE(.);
    KEEP (*(EXCLUDE_FILE (*crtend.* *crtbegin.*) .ctors SORT(.ctors.*)))
    __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(.);
    /* System init functions registered via ESP_SYSTEM_INIT_FN */
    _esp_system_init_fn_array_start = ABSOLUTE(.);
    KEEP (*(SORT_BY_INIT_PRIORITY(.esp_system_init_fn.*)))
    _esp_system_init_fn_array_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.*)
    _thread_local_end = ABSOLUTE(.);
    _rodata_reserved_end = ABSOLUTE(.);  /* This is a symbol marking the flash.rodata end, this can be used for mmu driver to maintain virtual address */
    . = ALIGN(4);
  } >default_rodata_seg

  _flash_rodata_align = ALIGNOF(.flash.rodata);

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

  .flash.text :
  {
    _stext = .;
    _instruction_reserved_start = ABSOLUTE(.);  /* This is a symbol marking the flash.text start, this can be used for mmu driver to maintain virtual address */
    _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
      */
    . += _esp_flash_mmap_prefetch_pad_size;

    _text_end = ABSOLUTE(.);
    _instruction_reserved_end = ABSOLUTE(.);  /* This is a symbol marking the flash.text end, this can be used for mmu driver to maintain virtual address */
    _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

  /* Marks the end of IRAM code segment */
  .iram0.text_end (NOLOAD) :
  {
    . = ALIGN (4);
    _iram_text_end = ABSOLUTE(.);
  } > iram0_0_seg

  .iram0.data :
  {
    . = ALIGN(4);
    _iram_data_start = ABSOLUTE(.);

    mapping[iram0_data]

    _iram_data_end = ABSOLUTE(.);
  } > iram0_0_seg

  .iram0.bss (NOLOAD) :
  {
    . = ALIGN(4);
    _iram_bss_start = ABSOLUTE(.);

    mapping[iram0_bss]

    _iram_bss_end = ABSOLUTE(.);
    . = ALIGN(4);
    _iram_end = ABSOLUTE(.);
   } > iram0_0_seg

  /* Marks the end of data, bss and possibly rodata  */
  .dram0.heap_start (NOLOAD) :
  {
    . = ALIGN (8);
    /* Lowest possible start address for the heap */
    _heap_low_start = ABSOLUTE(.);
  } > dram0_0_seg

  /** This section will be used by the debugger and disassembler to get more information
    * about raw data present in the code.
    * Indeed, it may be required to add some padding at some points in the code
    * in order to align a branch/jump destination on a particular bound.
    * Padding these instructions will generate null bytes that shall be
    * interpreted as data, and not code by the debugger or disassembler.
    * This section will only be present in the ELF file, not in the final binary
    * For more details, check GCC-212
    */
  .xt.prop 0 :
  {
    KEEP (*(.xt.prop .gnu.linkonce.prop.*))
  }

  .xt.lit 0 :
  {
    KEEP (*(.xt.lit .gnu.linkonce.p.*))
  }
}

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

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