Re: context switch vs. signal delivery [was: Re: Accelerating user mode linux]

From: Andi Kleen (ak@suse.de)
Date: Mon Aug 05 2002 - 17:16:05 EST


On Mon, Aug 05, 2002 at 11:09:41PM +0100, Jamie Lokier wrote:
> Andi Kleen wrote:
> > > 2: What happens when the user's signal handler decides it wants to save
> > > the FPU state itself (after all) and proceed with some FPU use. Will
> > > sigreturn restore the user-saved FPU state? Just curious.
> >
> > Nope it won't because there is no saved state. The previous context's FPU
> > state will be silently corrupted.
>
> I meant if the user's signal handler decides it wants to save the FPU
> state directly into the signal context struct, after deciding to do
> that. Won't that work?

In theory yes. The space should be already allocated on the stack, it just
has to be filled in.

-Andi
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