Messages in this thread | | | Date | Fri, 25 Jan 2013 14:58:35 +0100 | From | Olaf Hering <> | Subject | Re: [PATCH RESEND 1/1] X86: Handle Hyper-V vmbus interrupts as special hypervisor interrupts |
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On Fri, Jan 25, Jan Beulich wrote:
> >>> On 24.01.13 at 19:59, Olaf Hering <olaf@aepfle.de> wrote: > > On Thu, Jan 24, KY Srinivasan wrote: > > > > > >> > Question is - considering you stated that this is supported > >> > starting in Win8, doesn't Hyper-V itself announce that > >> > capability in some explicit way? > >> > >> Thanks Jan. Unfortunately I don't think tis interrupt delivery model > >> is specified via a "feature" bit (I will check with the Windows guys). > >> Perhaps, we can have a Hyper-V specific compilation switch to address > >> the Xen emulation issue. > > > > Would that really help if both pvops XEN_PVHVM and HYPERV are enabled in > > the config? I assume at this point the access to the DMI data is not yet > > possible. > > As just said in another reply - with XEN_PVHVM, there's no problem, > since Xen gets checked for first. There's only a problem when > !XEN_PVHVM, because in that case Hyper-V will be probed for. > And the problem can only get bigger when on top of that the > out-of-tree PV drivers are intended to be used.
Yes, xen_cpuid_base() recognizes Xen as hypervisor even with 'viridian=1' in the .cfg file. I think if there is no feature bit for this, the DMI can be used because its appearently available before the host is checked:
... [ 0.000000] NX (Execute Disable) protection: active [ 0.000000] DMI 2.4 present. [ 0.000000] DMI: Xen HVM domU, BIOS 4.1.3_06-0.7.1 12/05/2012 [ 0.000000] Hypervisor detected: Microsoft HyperV [ 0.000000] HyperV: features 0x70, hints 0x0 [ 0.000000] e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved) ...
Olaf
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