RE: [Xen-devel] iommu=0 leading to panic when system defaults to using x2apic

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Yes, X2apic is depend on iommu. If disable iommu when using x2apic, it will 
trigger the panic.

best regards
yang

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Jan Beulich
> Sent: Friday, December 10, 2010 8:03 PM
> To: Keir Fraser
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] iommu=0 leading to panic when system defaults to
> using x2apic
> 
> >>> On 10.12.10 at 12:47, Keir Fraser <keir@xxxxxxx> wrote:
> > On 10/12/2010 10:58, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
> >
> >>>>> On 10.12.10 at 11:06, Keir Fraser <keir@xxxxxxx> wrote:
> >>> Are you looking at xen-4.0? I think you should look at latest xen-unstable
> >>
> >> I looked at 4.0 in parallel with -unstable (non-staging) as of
> >> yesterday.
> >
> > Even before yesterday, xen-unstable benefits from c/s 22388, which is
> > intended to work around the iommu=0/x2apic=0 dependency a bit. Not sure if
> > it is fully satisfactory. And it is not backported to 4.0 as yet because,
> > well, I don't understand this crap enough, basically.
> 
> Ah, yes, that makes it better (and I must then have looked at an
> older snapshot of -unstable instead).
> 
> Still, as you say, a lot of questions remain. On top of what you and
> I raised already, I wonder whether the APIC-ID-exceeding-8-bits
> case is really being handled correctly now when iommu=0.
> 
> Jan
> 
> 
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