Re: [PATCH] add virtio disk geometry feature

From: Ryan Harper
Date: Thu Apr 17 2008 - 10:37:55 EST


* Anthony Liguori <aliguori@xxxxxxxxxx> [2008-04-16 16:33]:
> Rusty Russell wrote:
> >On Thursday 17 April 2008 04:56:37 Ryan Harper wrote:
> >
> >>From: Ryan Harper <ryanh@xxxxxxxxxx>
> >>
> >>Rather than faking up some geometry, allow the backend to push the disk
> >>geometry via virtio pci config option. Keep the old geo code around for
> >>compatibility.
> >>
> >
> >Hi Ryan,
> >
> > Looks good! Some brief review below. Mainly just "how I would have done
> >things" stuff. BTW, does this help in real life? I assume something in
> >userspace wants it?
> >
>
> Boot loaders (like grub) query the geometry from the kernel to figure
> out how to setup the stage1/stage2. We've seen strange issues with grub
> thinking it has crazy geometries when installed on a virtio disk (as
> opposed to booting from virtio with an existing disk).
>
> Ryan: have you tested a hardy install with your patches? Does it help
> when installing to virtio? I could pretty reliably reproduce the
> strangeness with a 20GB disk image FWIW.

I had tested out hardy with a 10G disk and saw nothing out of the
ordinary. Disk size was the expected value and grub had no issues with
it.

--
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253 T/L: 678-9253
ryanh@xxxxxxxxxx
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