strange Bug

ba_f ba_f at rbg.informatik.tu-darmstadt.de
Wed Nov 12 00:11:38 CET 2014


Hello Hackers,


this is a following to the thread below, but i didnt wanna occupy it so 
i start a new one.
http://os.inf.tu-dresden.de/pipermail/l4-hackers/2014/007049.html
http://os.inf.tu-dresden.de/pipermail/l4-hackers/2014/007050.html


> This usually happens when you try to access an address with no memory
> mapped. From the address it looks like you are accessing an address
> right below your stack, i.e., you are exceeding L4Re's default stack
> size. Most likely you have a function with a large buffer on the stack
> or you are recursing very deeply?

Actually not.
There is a tiny buffer (4096 Bytes), and one function calles itself 
recursively one time.

> If that does not help, try increasing L4Re's default stack
> size for your application using the L4RE_ELF_AUX_ELEM_T macro defined
> in l4/re/elf_aux.h. For this, place something like this anywhere in
> your compilation unit:
> 
> #include <l4/re/elf_aux.h>
> L4RE_ELF_AUX_ELEM_T(l4re_elf_aux_mword_t, stack_size,
>                     L4RE_ELF_AUX_T_STACK_SIZE, 65536);
> 

Didn't work.
I even doubled the size.
There is just a tiny difference in the Error Message, which most likely 
comes from the extra code.

before:
>> L4Re[rm]: unhandled write page fault @7ffff300 pc=15c7a8
now:
>> L4Re[rm]: unhandled write page fault @7ffff2e0 pc=15c7a8

> you might want to use standard binutils (e.g., objdump) on your binary
> to find out what instruction is at the respective PC and map this to
> whatever function it belongs to in your code.

I only have a pc=115c7a8, but since i start from 0x01000000, i guess 
that right?
>> 115c7a8:       e28cca13        add     ip, ip, #77824  ; 0x13000

I couldn't find an image with debug information, so i dont know what 
C-code this belongs to.



Thanks,
ba_f



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