strange Bug

ba_f ba_f at rbg.informatik.tu-darmstadt.de
Wed Nov 12 21:09:50 CET 2014


Hello,

>> I couldn't find an image with debug information, so i dont know
>> what C-code this belongs to.
> 
> objdump's '-d' option did not help? Are you specifying your own
> compiler flags for this program? Otherwise, L4Re's build system by
> default compiles with debug info.

Indeed, i was objdumping the bootstrap.elf, which seems not to have 
Debug-Infos.
But i found Debug-infos here: obj/l4/arm-ca/bin/arm_armv7a/l4f/crapApp


>> I only have a pc=115c7a8, but since i start from 0x01000000, i
>> guess that right?
>>> 115c7a8:       e28cca13        add     ip, ip, #77824  ;
>>> 0x13000
> 
> No way. This instruction adds a constant to a register and does not
> touch memory at all. Hence it won't raise a page fault. Did you
> objdump your program for that?

I'm not sure what you mean. I'm not experienced with objdump, though. 
But i can't look at all Load & Store instructions, do i? Looking for 
pc=15c7a8 isn't the solution, neither, since it's not there.
So, what would u recommend to look for?


My problem again:
The function foo() is only called at one place in the code. I have to 
comment some stuff out in foo() to make the program work. But even if i 
dont call foo() (it is useless for this test-case), the program fails at 
the same place. So, the fault can't be in foo().

There are no threads, and no risky pointer stuff. Actually it is tested 
legacy code for Intel-Linux.



Thank u so far,

ba_f



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