[patch] allow switching stacks

[Andrew Cagney]

> Hi Everyone,
> 
> This patch against gdb-6.0 adds an option to disable an error check
> which reports a non-contiguous stack as corrupted. I need this
> option to get a reliable stack trace using kgdb on the x86-64 Linux
> kernel because it uses a separate per-processor interrupt stack.
> 
> This option is enabled with:
> 
>      set backtrace switch-stacks on
> 
> Jim Houston - Concurrent Computer Corp.

Can you provide more details of the problem -- exactly what do things 
look like at the stack switch?

Your problem sounds very similar to the combination of a signal altstack 
and a signal trampoline - for such a situtation the stack direction 
check isn't applicable (pointing to the real bug).

Andrew