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

[Wei Liu <wei.liu2@citrix.com>]

On Wed, Jun 01, 2016 at 03:34:08PM +0200, Olaf Hering wrote:
> On Wed, Jun 01, Wei Liu wrote:
> 
> > So I think the safest option now is to revert the said patch and figure
> > out what to do next.
> 
> What did OSStest report when c0c099d got into the tree? Do these test
> domU.cfg files contain vdev=hd instead of vdev=xvd, so the boot breakage
> was not noticed?
> 

OSStest always has hda for hvm guest.

> What are the options we have to define a disk connected to an PIIX or
> AHCI controller? I see xl.cfg has hdtype=. Is vdev hd vs. xvd really the
> best way to describe a PV-only disk? It looks like the answer is yes.

I would think so.

> hdtype= describes the controller variant, and vdev= the disk variant.
> 

Yes, you're correct. hdtype= is for controller.

> So in the end it needs to be documented properly that moving dom0 to
> xen-4.7 requires adjustments to vdev= in domU.cfg (xvd -> hd), and that
> this MAY have an impact for domU frontend drivers which use the vdev
> string as is.
> Namely this affects SLE11, SLE12, SLE12SP1, openSUSE up to Leap 42.1.
> Upcoming releases use a pvops based kernel, so the device names are
> fixed.
> Konrad mentioned Solaris, no idea if its frontend driver uses the vdev
> string. BSD should be checked as well.
> 

So you are fine with documenting without reverting the patch?

Wei.

> Olaf

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