Re: Freeze with KVM_CLOCK, undocumented dependency VIRTIO_BLK -> VIRTIO_PCI

[Anthony Liguori <anthony@codemonkey.ws>]

Bernhard Schmidt wrote:
> Hi,
>
> apologies if those questions have already been answered, I did not find
> anything specific that should still be visible.
>
> I'm currently testing KVM (kvm-0.70 package from Debian unstable,
> rebuilt on Ubuntu Hardy) on a Athlon64 in i386 mode and found two small
> issues while trying to build a small kernel for my guest systems
> (2.6.26-rc6).
>
> a) when I enable KVM_CLOCK in the kernel configuration the guest system
> freezes after
>
> PCI: Found IRQ 11 for device 0000:00:04.0
>  vda: vda1 vda2
> TCP cubic registered
> NET: Registered protocol family 10
> NET: Registered protocol family 17
> Using IPI Shortcut mode
>
> when I disable KVM_CLOCK it mounts the filesystem and boots just fine
>
> Using IPI Shortcut mode
> kjournald starting.  Commit interval 5 seconds
> EXT3-fs: mounted filesystem with ordered data mode.
>   

There are some outstanding patches for KVM_CLOCK that may fix this problem.

> b) apparently VIRTIO_BLK works only when VIRTIO_PCI and thus PCI is
> enabled in the kernel. Otherwise the vda* device is not visible and the
> guest does not find its root filesystem.
>
> Is this expected? If yes, is it possible to add the appropriate
> dependency in the kernel configuration or amend the description
> accordingly?
>   

VIRTIO_BLK doesn't depend on VIRTIO_PCI.  VIRTIO_PCI allows you use to 
virtio devices under KVM.

This is all documented FWIW in the Kconfig and in a number of places on 
the wiki.

Regards,

Anthony Liguori

> Thanks,
> Bernhard
>
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