From: Pavel Machek <pavel@ucw.cz>
To: Andi Kleen <ak@suse.de>
Cc: Avi Kivity <avi@qumranet.com>,
Glauber de Oliveira Costa <gcosta@redhat.com>,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
glommer@gmail.com, tglx@linutronix.de, mingo@elte.hu,
ehabkost@redhat.com, jeremy@goop.org, anthony@codemonkey.ws,
virtualization@lists.linux-foundation.org, rusty@rustcorp.com.au,
chrisw@sous-sol.org, rostedt@goodmis.org, hpa@zytor.com,
"Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [PATCH 4/8] unify paravirt parts of system.h
Date: Wed, 5 Dec 2007 16:30:17 +0000 [thread overview]
Message-ID: <20071205163017.GA4756@ucw.cz> (raw)
In-Reply-To: <20071204193432.GI11764@bingen.suse.de>
On Tue 2007-12-04 20:34:32, Andi Kleen wrote:
> On Tue, Dec 04, 2007 at 09:18:33PM +0200, Avi Kivity wrote:
> > Glauber de Oliveira Costa wrote:
> >> This patch moves the i386 control registers manipulation functions,
> >> wbinvd, and clts functions to system.h. They are essentially the same
> >> as in x86_64, except for the cr8 register, which we add.
> >>
> >> +
> >> +static inline unsigned long native_read_cr8(void)
> >> +{
> >> + unsigned long cr8;
> >> + asm volatile("mov %%cr8,%0" : "=r" (cr8), "=m" (__force_order));
> >> + return cr8;
> >> +}
> >> +
> >>
> >
> > There is no cr8 register on i386. This had better be protected by an
> > #ifdef.
> >
> > (you're likely not getting an error since it's a static inline, so the asm
> > is never emitted)
>
> Linux never uses that register. The only user is suspend save/restore,
> but that' bogus because it wasn't ever initialized by Linux in the first
> place. It could be probably all safely removed.
It probably is safe to remove... but we currently support '2.8.95
kernel loads/resumes 2.6.24 image'... which would break if 2.8 uses
cr8.
So please keep it if it is not a big problem.
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2007-12-15 7:55 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-04 16:06 [PATCH 0/8] Integrate system.h Glauber de Oliveira Costa
2007-12-04 16:06 ` [PATCH 1/8] remove volatile keyword from clflush Glauber de Oliveira Costa
2007-12-04 16:06 ` [PATCH 2/8] put together equal pieces of system.h Glauber de Oliveira Costa
2007-12-04 16:06 ` [PATCH 3/8] unify load_segment macro Glauber de Oliveira Costa
2007-12-04 16:06 ` [PATCH 4/8] unify paravirt parts of system.h Glauber de Oliveira Costa
2007-12-04 16:06 ` [PATCH 5/8] remove unused macro Glauber de Oliveira Costa
2007-12-04 16:06 ` [PATCH 6/8] unify smp parts of system.h Glauber de Oliveira Costa
2007-12-04 16:06 ` [PATCH 7/8] move switch_to macro to system.h Glauber de Oliveira Costa
2007-12-04 16:06 ` [PATCH 8/8] unify system.h Glauber de Oliveira Costa
2007-12-04 19:18 ` [PATCH 4/8] unify paravirt parts of system.h Avi Kivity
2007-12-04 19:34 ` Andi Kleen
2007-12-05 16:30 ` Pavel Machek [this message]
2007-12-15 13:17 ` Ingo Molnar
2007-12-17 0:27 ` Rafael J. Wysocki
2007-12-17 0:23 ` Pavel Machek
2007-12-17 0:58 ` Rafael J. Wysocki
2007-12-15 13:26 ` Andi Kleen
2007-12-15 22:54 ` Pavel Machek
2007-12-15 20:28 ` H. Peter Anvin
2007-12-04 19:41 ` Glauber de Oliveira Costa
2007-12-04 22:14 ` Denys Vlasenko
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