Re: [PATCH] add virtio disk geometry feature

[Ryan Harper <ryanh@us.ibm.com>]

* Anthony Liguori <aliguori@us.ibm.com> [2008-04-16 16:33]:
> Rusty Russell wrote:
> >On Thursday 17 April 2008 04:56:37 Ryan Harper wrote:
> >  
> >>From: Ryan Harper <ryanh@us.ibm.com>
> >>
> >>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@us.ibm.com