Re: [Xen-devel] fpu_taskswitch adjustment proposal

[Keir Fraser <keir@xxxxxxx>]

On 18/06/2012 08:32, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

>> It should be possible for the guest kernel to track its CR0.TS setting
>> shouldn't it? It gets modified only via a few paravirt hooks, and implicitly
>> cleared on #NM.
> 
> Sure, but selling this to the Linux maintainers I would expect to be
> harder than fitting the Xen side of things into the current save-
> and-restore model the native xor code uses. It would only be strait
> forward to implement on the legacy, forward ported trees.

Wouldn't it be hidden entirely behind pv_ops hooks and within Xen-specific
SSE save/restore code? I suppose you'd need to statically allocate the
per-cpu space for tracking the CR0.TS state... But overall it seems it will
be of little/no concern to other kernel maintainers?

 -- Keir

> However, with the #NM handler in pv-ops apparently not
> leveraging the fact that CR0.TS is already cleared for it on entry,
> maybe this could indeed be introduced together. Konrad?




_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel