stepping over longjmp

[Daniel Jacobowitz]

On Fri, Aug 04, 2006 at 08:11:32PM +1200, Nick Roberts wrote:
> 
> With current CVS GDB and Fedora Core 5 i686 i386 GNU/Linux (2.6.17-1.2157 but
> also 2.6.15) when I try to step over longjmp (using next) I get the following
> error:
> 
>   Warning:
>   Cannot insert breakpoint -59.
>   Error accessing memory address 0x226092c5: Input/output error.
> 
> ISTR that this was also the case with FC4 and have only recently realised that
> you can step usefully step over a longjmp call after trying it on Mandrake 9
> (2.4.19)
> 
> Is this a known kernel problem or a bug in GDB?

Has nothing to do with the kernel.  I imagine that this is the problem
I discussed on this list a while ago, CC'd to libc-alpha; glibc now
uses a canary in the jmp_buf which GDB has no way to access.

Does export LD_POINTER_GUARD=0 make a difference?

-- 
Daniel Jacobowitz
CodeSourcery