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From: Pavel Machek <pavel@ucw.cz>
To: Andi Kleen <andi@firstfloor.org>
Cc: Andi Kleen <ak@suse.de>, 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: Sat, 15 Dec 2007 23:54:19 +0100
Message-ID: <20071215225419.GB2434@elf.ucw.cz> (raw)
In-Reply-To: <20071215132638.GA28231@basil.nowhere.org>

On Sat 2007-12-15 14:26:38, Andi Kleen wrote:
> > 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.
> 
> No it won't. 2.8 would just restore some random useless value.

Restoring random value seems wrong. Putting random values into cpu
registers can break stuff, right?

Even if 2.6.24 image being restored did not set %cr8 itself, it may
depend on %cr8 to have "sane" value.

> If 2.8 wants to use CR8 it would have to re-initialize it

We are talking "2.8 restores 2.6 image" here.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  reply index

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
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 [this message]
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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