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xen-devel
Re: [Xen-devel] [PATCH] Make new PCI device probe work with older hyperv
As long as setups with older dom0 kernels do not suffer feature regression
when only the hypervisor is upgraded, I think it's fine.
-- Keir
On 7/7/08 14:54, "Espen Skoglund" <espen.skoglund@xxxxxxxxxxxxx> wrote:
> For older dom0 kernels Xen will not know which PCI devices exists in
> the system. This has the implication that
>
> a) IOMMU device assignment will not work, and
> b) assigning MSI interrupts will not work.
>
> The only way to avoid these "limitations" is to either perform PCI bus
> enumaration at startup or to create new pci_devs on deamand (e.g.,
> when guest wants to assign an MSI to a new unknown device).
>
> Given that MSIs (and to a lesser extent IOMMUs) have only recently
> found their way into Xen, I'm not sure whether it calls for having to
> support a-few-weeks-old dom0s in Xen.
>
> eSk
>
>
> [Keir Fraser]
>> Thanks. One thing also -- do old dom0 kernels work with new Xen
>> (i.e., do we have compatibility both ways)?
>
>> -- Keir
>
>> On 7/7/08 13:40, "Espen Skoglund" <espen.skoglund@xxxxxxxxxxxxx> wrote:
>
>>> Be a bit more forgiving if hyervisor does not implement the
>>> manage_pci_add hypercall.
>>>
>>> Signed-off-by: Espen Skoglund <espen.skoglund@xxxxxxxxxxxxx>
>>>
>>> --
>>> diff -r bb937c2f7382 drivers/xen/core/pci.c
>>> --- a/drivers/xen/core/pci.c Fri Jul 04 17:55:07 2008 +0100
>>> +++ b/drivers/xen/core/pci.c Mon Jul 07 13:34:32 2008 +0100
>>> @@ -19,7 +19,7 @@
>>> manage_pci.devfn = pci_dev->devfn;
>>>
>>> r = HYPERVISOR_physdev_op(PHYSDEVOP_manage_pci_add, &manage_pci);
>>> - if (r)
>>> + if (r && r != -ENOSYS)
>>> return r;
>>>
>>> r = pci_bus_probe(dev);
>>>
>>> _______________________________________________
>>> Xen-devel mailing list
>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>> http://lists.xensource.com/xen-devel
>
>
>
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