ESP32 Backtrace
When the esp32 crashes it often generates a "Guru meditation error" and prints the register contents as well as a backtrace, for example:
Guru Meditation Error: Core 0 panic'ed (Unhandled debug exception)
Debug exception reason: Stack canary watchpoint triggered (Tmr Svc)
Core 0 register dump:
PC : 0x40081708 PS : 0x00060336 A0 : 0x3ffbc990 A1 : 0x3ffbc8d0
A2 : 0x3ffb7dd0 A3 : 0x00000000 A4 : 0x3ffb7e18 A5 : 0x00000000
A6 : 0x00000001 A7 : 0x00000018 A8 : 0x800894ac A9 : 0x3ffbc970
A10 : 0x00000000 A11 : 0x3ffc12c8 A12 : 0x3ffc12c8 A13 : 0x00000001
A14 : 0x00060320 A15 : 0x00000000 SAR : 0x00000002 EXCCAUSE: 0x00000001
EXCVADDR: 0x00000000 LBEG : 0x40001609 LEND : 0x4000160d LCOUNT : 0x00000000
Backtrace: 0x40081708:0x3ffbc8d0 0x3ffbc98d:0x3ffbc9d0 0x400d85b6:0x3ffbc9f0 0x40082926:0x3ffbca10 0
x400822fe:0x3ffbca30 0x400dd591:0x3ffbcaa0 0x400dc019:0x3ffbcac0 0x400dc467:0x3ffbcae0 0x400dc5f5:0x
3ffbcb50 0x400db105:0x3ffbcbd0 0x400db1b4:0x3ffbcc50 0x400da27e:0x3ffbccb0 0x400da7b1:0x3ffbccf0 0x4
01396b2:0x3ffbcd10 0x401398a6:0x3ffbcd60 0x401398f9:0x3ffbcd90 0x401017ec:0x3ffbcdb0 0x401019fa:0x3f
fbcde0 0x400d9721:0x3ffbce10 0x400
The PC register provides information about where the execution crashed and the backtrace line additionally provides the locations in the current task's call stack. All those numbers can be decoded and matched with source line numbers using a simple tool and the "elf" file for the firmware as long as the firmware was compiled with the -g compiler option. (Currently this requires the DEBUG=1 parameter to make.)
One simple tool is a bash shell script from https://github.com/tve/esp32-backtrace: the script expects the register dump and backtrace line to be pasted into its stdin and it uses gdb to inspect the elf file and print the source lines. For example:
PC: 0x40081708 is at esp-idf-public/components/freertos/xtensa_vectors.S:1118.
BT-0: 0x40081708 is at esp-idf-public/components/freertos/xtensa_vectors.S:1118.
BT-2: 0x400d85b6 is in esp_ipc_call (esp-idf-public/components/esp32/ipc.c:123).
BT-3: 0x40082926 is in spi_flash_disable_interrupts_caches_and_other_cpu (esp-idf-public/components/
spi_flash/cache_utils.c:120).
BT-4: 0x400822fe is in spi_flash_read (esp-idf-public/components/spi_flash/flash_ops.c:154).
BT-5: 0x400dd591 is in nvs::nvs_flash_read(unsigned int, void*, unsigned int) (esp-idf-public/compon
ents/nvs_flash/src/nvs_ops.cpp:70).
BT-6: 0x400dc019 is in nvs::Page::readEntry(unsigned int, nvs::Item&) const (esp-idf-public/componen
ts/nvs_flash/src/nvs_page.cpp:717).
BT-7: 0x400dc467 is in nvs::Page::findItem(unsigned char, nvs::ItemType, char const*, unsigned int&,
nvs::Item&, unsigned char, nvs::VerOffset) (esp-idf-public/components/nvs_flash/src/nvs_page.cpp:76
1).
BT-8: 0x400dc5f5 is in nvs::Page::readItem(unsigned char, nvs::ItemType, char const*, void*, unsigne
d int, unsigned char, nvs::VerOffset) (esp-idf-public/components/nvs_flash/src/nvs_page.cpp:266).
BT-9: 0x400db105 is in nvs::Storage::readMultiPageBlob(unsigned char, char const*, void*, unsigned i
nt) (esp-idf-public/components/nvs_flash/src/nvs_storage.cpp:430).
BT-10: 0x400db1b4 is in nvs::Storage::readItem(unsigned char, nvs::ItemType, char const*, void*, uns
igned int) (esp-idf-public/components/nvs_flash/src/nvs_storage.cpp:455).
BT-11: 0x400da27e is in nvs_get_str_or_blob(nvs_handle, nvs::ItemType, char const*, void*, size_t*)
(esp-idf-public/components/nvs_flash/src/nvs_api.cpp:515).
BT-12: 0x400da7b1 is in nvs_get_blob(nvs_handle, char const*, void*, size_t*) (esp-idf-public/compon
ents/nvs_flash/src/nvs_api.cpp:525).
BT-18: 0x400d9721 is in esp_wifi_init (esp-idf-public/components/esp32/wifi_init.c:51).
BT-24: 0x4008b3ba is in prvProcessExpiredTimer (esp-idf-public/components/freertos/timers.c:524).
BT-25: 0x4008b3ed is in prvProcessTimerOrBlockTask (esp-idf-public/components/freertos/timers.c:571)
.
BT-26: 0x4008b508 is in prvTimerTask (esp-idf-public/components/freertos/timers.c:544).
BT-27: 0x40088781 is in vPortTaskWrapper (esp-idf-public/components/freertos/port.c:143).
The are other similar scripts/programs, for example https://github.com/me-no-dev/EspExceptionDecoder