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Date: Tue, 6 Aug 2002 00:16:05 +0200
From: Andi Kleen <ak@suse.de>
To: Jamie Lokier <lk@tantalophile.demon.co.uk>
Cc: Andi Kleen <ak@suse.de>, Linus Torvalds <torvalds@transmeta.com>,
       linux-kernel@vger.kernel.org
Subject: Re: context switch vs. signal delivery [was: Re: Accelerating user  mode linux]
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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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