From: Dave McCracken <dcm@mccr.org>
To: xen-devel@lists.xensource.com
Cc: Keir Fraser <keir.fraser@eu.citrix.com>
Subject: Re: Re: [PATCH 2/2] Linux support for hugepages as a Xen PV guest
Date: Wed, 15 Oct 2008 12:01:06 -0500 [thread overview]
Message-ID: <200810151201.06367.dcm@mccr.org> (raw)
In-Reply-To: <200810101006.44389.dcm@mccr.org>
On Friday 10 October 2008, Dave McCracken wrote:
> On Friday 10 October 2008, Keir Fraser wrote:
> > hugetlbfs should only be enabled at runtime if supported by the
> > hypervisor. Perhaps we can enable the PSE CPUID flag if the hypervisor
> > supports superpages?
>
> I'll look into it.
Opening the cover to this exposed some very interesting things on the Linux
side.
For starters, Xen currently does remove PSE from the CPUID it returns to the
guest. I'll add some code to allow PSE when hugepages are enabled.
Second, in Linux for the x86_64 architecture the macro to check for PSE is
hard-wired to always be true.
Third, hugepages in Linux makes no check whatsoever for the presence or
absence of PSE. It assumes it's there.
I'll look into the simplest way to make the various Linux parts obey the PSE
flag properly.
Dave McCracken
Oracle Corp.
This is all for the Linux-xen-2.6.18 tree on xensource.
next prev parent reply other threads:[~2008-10-15 17:01 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-10 13:29 [PATCH 1/2] Xen PV support for hugepages dcm
2008-10-10 13:30 ` [PATCH 2/2] Linux support for hugepages as a Xen PV guest dcm
2008-10-10 13:38 ` Keir Fraser
2008-10-10 15:06 ` Dave McCracken
2008-10-10 15:35 ` [PATCH 2/2] Linux support for hugepages as a Xen PVguest Jan Beulich
2008-10-15 17:01 ` Dave McCracken [this message]
2008-10-15 21:48 ` Re: [PATCH 2/2] Linux support for hugepages as a Xen PV guest Jeremy Fitzhardinge
2008-10-15 22:12 ` Dave McCracken
2008-10-15 22:31 ` Jeremy Fitzhardinge
2008-10-10 15:32 ` [PATCH 2/2] Linux support for hugepages as a Xen PVguest Jan Beulich
2008-10-10 15:28 ` [PATCH 1/2] Xen PV support for hugepages Jan Beulich
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