Before this change _invalid_pc_placeholder pointed to address of _init
function from crti.o
This made GDB input a bit confusing:
0x40080400 in _init ()
(gdb) bt
#0 0x40080400 in _init ()
#1 0x400e519a in test_instr_fetch_prohibited () at /home/alex/git/esp-idf/tools/test_apps/system/panic/main/test_panic.c:271
#2 0x400d89a7 in app_main () at /home/alex/git/esp-idf/tools/test_apps/system/panic/main/test_app_main.c:116
#3 0x400e5f22 in main_task (args=0x0) at /home/alex/git/esp-idf/components/freertos/app_startup.c:208
#4 0x400895a8 in vPortTaskWrapper (pxCode=0x400e5eb0 <main_task>, pvParameters=0x0) at /home/alex/git/esp-idf/components/freertos/FreeRTOS-Kernel/portable/xtensa/port.c:139
After the change GDB prints output that contains a hint:
_invalid_pc_placeholder () at /home/alex/git/esp-idf/components/xtensa/xtensa_vectors.S:2235
2235 UNREACHABLE_INSTRUCTION_CHECK_PREVIOUS_FRAMES
(gdb) bt
#0 _invalid_pc_placeholder () at /home/alex/git/esp-idf/components/xtensa/xtensa_vectors.S:2235
#1 0x400e519e in test_instr_fetch_prohibited () at /home/alex/git/esp-idf/tools/test_apps/system/panic/main/test_panic.c:271
#2 0x400d89ab in app_main () at /home/alex/git/esp-idf/tools/test_apps/system/panic/main/test_app_main.c:116
#3 0x400e5f26 in main_task (args=0x0) at /home/alex/git/esp-idf/components/freertos/app_startup.c:208
#4 0x400895a8 in vPortTaskWrapper (pxCode=0x400e5eb4 <main_task>, pvParameters=0x0) at /home/alex/git/esp-idf/components/freertos/FreeRTOS-Kernel/portable/xtensa/port.c:139
ERROR:
A fatal error occurred: Segment loaded at 0x3c01d150 lands in same 64KB flash
mapping as segment loaded at 0x3c018020. Can't generate binary. Suggest
changing linker script or ELF to merge sections.
Seems binary generator does not handle well empty sections that contains
aligning only. I did not investigate much but this change helped.
