esp-hal/esp32s3-hal/ld/memory.x

/* override entry point */
ENTRY(ESP32Reset)

/* reserved at the start of DRAM */
RESERVE_DRAM = 0x8000;

/* reserved at the start of the RTC memories for use by the ULP processor */
RESERVE_RTC_FAST = 0;
RESERVE_RTC_SLOW = 0;

/* define stack size for both cores */
STACK_SIZE = 8k;

/* Specify main memory areas */
MEMORY
{
  vectors_seg ( RX )     : ORIGIN = 0x40370000 + RESERVE_DRAM, len =  1k
  iram_seg ( RX )        : ORIGIN = 0x40370400 + RESERVE_DRAM, len = 328k - 0x400

  dram_seg ( RW )        : ORIGIN = 0x3FC80000 + RESERVE_DRAM, len = 328k - RESERVE_DRAM
  reserved_for_boot_seg  : ORIGIN = 0x3FFDC200, len = 144k /* ???? SRAM1; reserved for static ROM usage; can be used for heap */

  /* external flash 
     The 0x20 offset is a convenience for the app binary image generation.
     Flash cache has 64KB pages. The .bin file which is flashed to the chip
     has a 0x18 byte file header, and each segment has a 0x08 byte segment
     header. Setting this offset makes it simple to meet the flash cache MMU's
     constraint that (paddr % 64KB == vaddr % 64KB).)
  */
  irom_seg ( RX )        : ORIGIN = 0x42000020, len = 4M - 0x20
  drom_seg ( R )         : ORIGIN = 0x3C000020, len = 4M - 0x20


  /* RTC fast memory (executable). Persists over deep sleep. Only for core 0 (PRO_CPU) */
  rtc_fast_iram_seg(RWX) : ORIGIN = 0x600fe000, len = 8k

  /* RTC fast memory (same block as above), viewed from data bus. Only for core 0 (PRO_CPU) */
  rtc_fast_dram_seg(RW)  : ORIGIN = 0x600fe000 + RESERVE_RTC_FAST, len = 8k - RESERVE_RTC_FAST

  /* RTC slow memory (data accessible). Persists over deep sleep. */
  rtc_slow_seg(RW)       : ORIGIN = 0x50000000 + RESERVE_RTC_SLOW, len = 8k - RESERVE_RTC_SLOW

  /* external memory, including data and text */
  psram_seg(RWX)         : ORIGIN =  0x3F500000, len = 0xA80000 /* ??? */
}

/* map generic regions to output sections */
INCLUDE "alias.x"

/* esp32 specific regions */
SECTIONS {
  .rtc_fast.text : {
   . = ALIGN(4);
    *(.rtc_fast.literal .rtc_fast.text .rtc_fast.literal.* .rtc_fast.text.*)
  } > rtc_fast_iram_seg AT > RODATA

  /*
    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_fast.dummy (NOLOAD) :
  {
    _rtc_dummy_start = ABSOLUTE(.); /* needed to make section proper size */
    . = SIZEOF(.rtc_fast.text);
    _rtc_dummy_end = ABSOLUTE(.); /* needed to make section proper size */
  } > rtc_fast_dram_seg
  
  
  .rtc_fast.data :
  {
    . = ALIGN(4);
    _rtc_fast_data_start = ABSOLUTE(.);
    *(.rtc_fast.data .rtc_fast.data.*)
    _rtc_fast_data_end = ABSOLUTE(.);
  } > rtc_fast_dram_seg AT > RODATA

 .rtc_fast.bss (NOLOAD) :
  {
    . = ALIGN(4);
    _rtc_fast_bss_start = ABSOLUTE(.);
    *(.rtc_fast.bss .rtc_fast.bss.*)
    _rtc_fast_bss_end = ABSOLUTE(.);
  } > rtc_fast_dram_seg

 .rtc_fast.noinit (NOLOAD) :
  {
    . = ALIGN(4);
    *(.rtc_fast.noinit .rtc_fast.noinit.*)
  } > rtc_fast_dram_seg


 .rtc_slow.text : {
   . = ALIGN(4);
    *(.rtc_slow.literal .rtc_slow.text .rtc_slow.literal.* .rtc_slow.text.*)
  } > rtc_slow_seg AT > RODATA

  .rtc_slow.data :
  {
    . = ALIGN(4);
    _rtc_slow_data_start = ABSOLUTE(.);
    *(.rtc_slow.data .rtc_slow.data.*)
    _rtc_slow_data_end = ABSOLUTE(.);
  } > rtc_slow_seg AT > RODATA

 .rtc_slow.bss (NOLOAD) :
  {
    . = ALIGN(4);
    _rtc_slow_bss_start = ABSOLUTE(.);
    *(.rtc_slow.bss .rtc_slow.bss.*)
    _rtc_slow_bss_end = ABSOLUTE(.);
  } > rtc_slow_seg

 .rtc_slow.noinit (NOLOAD) :
  {
    . = ALIGN(4);
    *(.rtc_slow.noinit .rtc_slow.noinit.*)
  } > rtc_slow_seg

 .external.data :
  {
    _external_data_start = ABSOLUTE(.);
    . = ALIGN(4);
    *(.external.data .external.data.*)
    _external_data_end = ABSOLUTE(.);
  } > psram_seg AT > RODATA

 .external.bss (NOLOAD) :
  {
    _external_bss_start = ABSOLUTE(.);
    . = ALIGN(4);
    *(.external.bss .external.bss.*)
    _external_bss_end = ABSOLUTE(.);
  } > psram_seg

 .external.noinit (NOLOAD) :
  {
    . = ALIGN(4);
    *(.external.noinit .external.noinit.*)
  } > psram_seg

  /* must be last segment using psram_seg */
  .external_heap_start (NOLOAD) :
  {
    . = ALIGN (4);
    _external_heap_start = ABSOLUTE(.);
  } > psram_seg 
} 

_external_ram_start = ABSOLUTE(ORIGIN(psram_seg));
_external_ram_end = ABSOLUTE(ORIGIN(psram_seg)+LENGTH(psram_seg));

_heap_end = ABSOLUTE(ORIGIN(dram_seg))+LENGTH(dram_seg)+LENGTH(reserved_for_boot_seg) - 2*STACK_SIZE;
_text_heap_end = ABSOLUTE(ORIGIN(iram_seg)+LENGTH(iram_seg));
_external_heap_end = ABSOLUTE(ORIGIN(psram_seg)+LENGTH(psram_seg));

_stack_start_cpu1 = _heap_end;
_stack_end_cpu1 = _stack_start_cpu1 + STACK_SIZE;
_stack_start_cpu0 = _stack_end_cpu1;
_stack_end_cpu0 = _stack_start_cpu0 + STACK_SIZE;

EXTERN(DefaultHandler);

INCLUDE "device.x"