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]
Date: Mon, 5 Aug 2002 23:35:42 +0200 [thread overview]
Message-ID: <20020805233542.A12753@wotan.suse.de> (raw)
In-Reply-To: <20020805223006.A8773@kushida.apsleyroad.org>
On Mon, Aug 05, 2002 at 10:30:06PM +0100, Jamie Lokier wrote:
> Andi Kleen wrote:
> > + err |= setup_sigcontext(&frame->sc, &frame->fpstate, regs, set->sig[0],
> > + (ka->sa.sa_flags&SA_NOFP));
>
> > err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
> > - regs, set->sig[0]);
> > + regs, set->sig[0], !!(ka->sa.sa_flags&SA_NOFP));
>
> 1: Why the inconsistency between the two ways the SA_NOFP flag is checked?
I don't remember. Probably there was some reason in an earlier version
of the code. The !! could be probably removed now.
>
> 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.
-Andi
next prev parent reply other threads:[~2002-08-05 21:32 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20020805163910.C7130@kushida.apsleyroad.org.suse.lists.linux.kernel>
[not found] ` <Pine.LNX.4.44.0208050922570.1753-100000@home.transmeta.com.suse.lists.linux.kernel>
2002-08-05 16:46 ` Andi Kleen
2002-08-05 21:30 ` Jamie Lokier
2002-08-05 21:35 ` Andi Kleen [this message]
2002-08-05 22:09 ` Jamie Lokier
2002-08-05 22:16 ` Andi Kleen
[not found] <1028294887.18635.71.camel@irongate.swansea.linux.org.uk.suse.lists.linux.kernel>
[not found] ` <Pine.LNX.4.44.0208031332120.7531-100000@localhost.localdomain.suse.lists.linux.kernel>
[not found] ` <m3u1mb5df3.fsf@averell.firstfloor.org.suse.lists.linux.kernel>
[not found] ` <ail2qh$bf0$1@penguin.transmeta.com.suse.lists.linux.kernel>
2002-08-05 8:38 ` Andi Kleen
2002-08-05 14:24 ` Jeff Dike
2002-08-05 16:19 ` Linus Torvalds
2002-08-02 13:28 Accelerating user mode linux Alan Cox
2002-08-03 11:38 ` context switch vs. signal delivery [was: Re: Accelerating user mode linux] Ingo Molnar
2002-08-04 6:46 ` Andi Kleen
2002-08-05 5:35 ` Linus Torvalds
2002-08-05 5:42 ` Arnaldo Carvalho de Melo
2002-08-05 6:37 ` Lincoln Dale
2002-08-05 15:39 ` Jamie Lokier
2002-08-05 16:38 ` Linus Torvalds
2002-08-06 5:31 ` Mark Mielke
2002-08-05 10:40 ` Ingo Molnar
2002-08-05 14:59 ` Larry McVoy
2002-08-05 15:41 ` Jamie Lokier
2002-08-05 15:44 ` Jamie Lokier
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