Re: 4.7 qemu regression: HVM guests fail to boot from xvda

[Olaf Hering <olaf@aepfle.de>]

On Tue, May 31, George Dunlap wrote:

> Sorry, can you expand on this a bit?  Are you saying that on SuSE, if
> you specify "vdev=xvda" in your config file, that you'll get PV
> devices named "/dev/xvda", but that if you specify "vdev=hda", that
> you'll get PV devices but named "/dev/hda"?

Yes, thats exactly what the xenlinux block frontend does.
pvops forces xvda, independent of the name 'vdev' in domU.cfg.
Up to xen-4.2 'vdev=hd*' was required to tell qemu to create an emulated
disk to boot from. Starting with xen-4.3 qemu also recognized
'vdev=xvd*' for the emulated disk. And starting with xen-4.7 qemu
requires 'xvda=hd*' again.

I think if some domU.cfg for xen-4.3+ has 'vdev=xvd*' and the domU uses
for some reason kernel names in config files and the domU uses a
xenlinux kernel, then changing domU.cfg to 'hd*' will allow the guest to
boot again. But its userland will miss the /dev/xvd* device nodes.
That probably remained unnoticed during testing the referenced commit if
a pvops based kernel was used.

Olaf

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