Re: maxima: debugging unaligned access

[Zan Lynx <zlynx@acm.org>]

On 1/26/10 3:29 PM, Camm Maguire wrote:
> Greetings, ad thanks for your helpful suggestions.  Having a bit of
> trouble.
>
> All this is in merulo chroot sid with gcc 4.4 at -O2.
>
> Outside gdb:
>
> 133/133 tests passed.
> Running tests in rtest8: maxima(18072): unaligned access to 0x600000000412c8b8, ip=0x200000000051de70
> Bus error
>
> Inside gdb, the program does not stop at this point with a bus error,
> but dies later due to memory corruption.
>
> 1)  Can I instruct gdb to stop at any such unaligned access?
>
> I guessed:
>
> (gdb) b *0x600000000412c8b8
> Can't insert breakpoint for slot numbers greater than 2.
>
> (gdb) b *0x600000000412c8b1
> Breakpoint 3 at 0x600000000412c8b1
>
> then reran, but gdb fell over:

The 0x6... addr is the data. You cannot execute data so you cannot 
breakpoint there (you could set a watchpoint though).

Use the 0x200000000051de70 addr instead.

--
Zan Lynx
zlynx@acm.org

"Knowledge is Power.  Power Corrupts.  Study Hard.  Be Evil."