This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] [Patch 2/4] Refining Xsave/Xrestore support

>>> On 28.10.10 at 09:55, Haitao Shan <maillists.shan@xxxxxxxxx> wrote:
> In my patch, if processor supports CR4.OSXSAVE, Xen will enable it and
> won't clear it as long as we are in ROOT mode.

Ah, okay. There's one problem with this, however - a pv domain the
kernel of which doesn't support xsave would still see CPUID report
the OSXSAVE bit set, and hence applications could be lead to
believe they can use the wider registers. I realize this also puts
under question our model of having the kernel look at CPUID's
OSXSAVE bit, but that could possibly be dealt with by having
pv_cpuid() (and perhaps xc_cpuid_pv_policy()) set the bit in case
Xen supports xsave.


Xen-devel mailing list