Re: [PATCH] x86: push old stack address on irqstack for unwinder

[H. Peter Anvin]

Martin Hicks wrote:
> Hi,
>
> KDB was using this information.  Could this be pushed towards 2.6.29 please?
>
> This re-adds the old stack pointer to the top of the irqstack to help
> with unwinding.  It was removed in commit d99015b1abbad743aa049b439c1e1dede6d0fa49
> as part of the save_args out-of-line work.

This bothers me... why should we add even a single instruction to what 
is arguably the single hottest path in the kernel to support an 
out-of-tree debugger, especially if kgdb (which is in-tree) doesn't need it?

What does kgdb do differently (or is kgdb broken too)?

	-hpa
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