debugging - GDB doesn't disassemble program running in RAM correctly -


i have application compiled using gcc stm32f407 arm processor. linker stores in flash, executed in ram. small bootstrap program copies application flash ram , branches application's resethandler.

memcpy(appramstart, appflashstart, appramsize);  // run application __asm volatile (     "ldr  r1, =_app_ram_start\n\t"    // load pointer application's vectors     "add  r1, #4\n\t"                 // increment vector pointer second entry (resethandler pointer)     "ldr  r2, [r1, #0x0]\n\t"         // load resethandler address via vector pointer                                       // bit[0] must 1 thumb instructions otherwise bus error occur.     "bx   r2"                         // jump resethandler - not return here );

this works ok, except when try debug application ram (using gdb eclipse) disassembly incorrect. curious thing debugger gets source code correct, , accept , halt on breakpoints have set. can single step source code lines. however, when single step assembly instructions, make no sense @ all. contains numerous undefined instructions. i'm assuming kind of alignment problem, looks correct me. suggestions?

it possible gdb relies on symbol table check instruction set mode can thumb(2)/arm. when move code ram can't find information , opts arm mode.

you can use set arm force-mode thumb in gdb force thumb mode instruction.

as side note, if illegal instruction when debugging arm binary problem if not complete nonsense trying disassembly data parts.

i find strange tools doesn't try heuristic approach when disassembling arm binaries. in case of auto shouldn't hard try both modes , error count decide mode use last resort.


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