From: Gerd Hoffmann <kraxel@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Jan Beulich <JBeulich@novell.com>,
Jeremy Fitzhardinge <jeremy@goop.org>,
Xen-devel <xen-devel@lists.xensource.com>,
the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jesse Barnes <jbarnes@virtuousgeek.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [Xen-devel] Re: [GIT PULL] xen /proc/mtrr implementation
Date: Wed, 20 May 2009 10:01:45 +0200 [thread overview]
Message-ID: <4A13B8E9.9060703@redhat.com> (raw)
In-Reply-To: <20090519152456.GB21271@elte.hu>
On 05/19/09 17:24, Ingo Molnar wrote:
> the Xen hypervisor can simply repeat all requests (i.e. not care at
> all about the fact that a guest does these modifications on all CPUs
> it sees), or realize that the modification has already been done and
> skip it.
Could be done, yes. It still feels wrong that wrmsr(mtrr) works
slightly different on xen and on native. And it wouldn't work on
existing Xen deployments as the Xen hypervisor doesn't support that today.
>>>>> Yeah, the third one is to not touch MTRRs after bootup and use PAT.
> That's a really old CPU, but even Coppermine has PAT support in the
> CPU. You need to go back to things like P5 200 MHz CPUs to find
> PAT-less CPUs.
Linux shouln't say "PAT not supported by CPU." then.
Also it doesn't make sense to me to handle things differently on native
and xen. While it might make sense to deprecate mtrrs in favor of PAT
(don't know enougth about all the different cpus in the wild to justify
that) I don't think it makes sense to do that for xen only. Native
should declare mtrrs obsolete as well.
cheers,
Gerd
next prev parent reply other threads:[~2009-05-20 8:04 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-12 23:27 [GIT PULL] xen /proc/mtrr implementation Jeremy Fitzhardinge
2009-05-12 23:27 ` [PATCH 1/6] xen: set cpu_callout_mask to make mtrr work Jeremy Fitzhardinge
2009-05-12 23:27 ` [PATCH 2/6] xen mtrr: Use specific cpu_has_foo macros instead of generic cpu_has() Jeremy Fitzhardinge
2009-05-12 23:27 ` [PATCH 3/6] xen mtrr: Use generic_validate_add_page() Jeremy Fitzhardinge
2009-05-12 23:27 ` [PATCH 4/6] xen mtrr: Implement xen_get_free_region() Jeremy Fitzhardinge
2009-05-12 23:27 ` [PATCH 5/6] xen mtrr: Add xen_{get,set}_mtrr() implementations Jeremy Fitzhardinge
2009-05-12 23:27 ` [PATCH 6/6] xen mtrr: Kill some unnecessary includes Jeremy Fitzhardinge
2009-05-13 13:30 ` [GIT PULL] xen /proc/mtrr implementation Ingo Molnar
2009-05-13 14:39 ` Jeremy Fitzhardinge
2009-05-15 18:27 ` Ingo Molnar
2009-05-15 20:09 ` Jeremy Fitzhardinge
2009-05-15 23:26 ` Eric W. Biederman
2009-05-15 23:49 ` Jeremy Fitzhardinge
2009-05-16 3:22 ` Jesse Barnes
2009-05-16 4:26 ` Eric W. Biederman
2009-05-16 18:22 ` Jesse Barnes
2009-05-18 5:02 ` Jeremy Fitzhardinge
2009-05-18 4:57 ` Jeremy Fitzhardinge
2009-05-18 8:59 ` Ingo Molnar
2009-05-18 13:17 ` [Xen-devel] " Jan Beulich
2009-05-18 17:51 ` Chris Wright
2009-05-18 18:07 ` Jeremy Fitzhardinge
2009-05-19 9:59 ` Ingo Molnar
2009-05-19 10:22 ` [Xen-devel] " Jan Beulich
2009-05-19 11:08 ` Ingo Molnar
2009-05-19 12:04 ` Gerd Hoffmann
2009-05-19 12:26 ` Ingo Molnar
2009-05-19 12:32 ` Alan Cox
2009-05-19 12:37 ` Ingo Molnar
2009-05-19 13:21 ` Gerd Hoffmann
2009-05-19 13:31 ` Ingo Molnar
2009-05-19 13:51 ` Gerd Hoffmann
2009-05-19 14:17 ` Ingo Molnar
2009-05-19 14:55 ` Gerd Hoffmann
2009-05-19 15:24 ` Ingo Molnar
2009-05-20 8:01 ` Gerd Hoffmann [this message]
2009-05-20 16:35 ` Jeremy Fitzhardinge
2009-05-20 16:12 ` Jeremy Fitzhardinge
2009-05-20 8:16 ` Andi Kleen
2009-05-20 16:39 ` Jeremy Fitzhardinge
2009-05-20 22:52 ` Andi Kleen
2009-05-20 22:49 ` Jeremy Fitzhardinge
2009-05-20 23:03 ` H. Peter Anvin
-- strict thread matches above, loose matches on Subject: below --
2009-05-25 8:42 [Xen-devel] " Tomasz Chmielewski
2009-05-25 9:15 ` Andi Kleen
2009-05-25 9:31 ` Jan Beulich
2009-05-25 9:47 ` Andi Kleen
2009-05-25 16:05 ` H. Peter Anvin
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