Re: [PATCH] Support RAID on virtio devices, and others

[Colin Watson <cjwatson@ubuntu.com>]

On Sun, Oct 25, 2009 at 10:27:49AM +0100, Vladimir 'phcoder' Serbinenko wrote:
> Colin Watson wrote:
> > GRUB only supports RAID on a relatively small number of device types, as
> > implemented by grub_util_getdiskname. I received a bug report noting
> > that this doesn't work for RAID arrays with virtio block devices (often
> > used in kvm) as components. This is difficult to support using the
> > approach taken by grub_util_getdiskname, as virtio devices use dynamic
> > major numbers.
> >
> > find_root_device in util/getroot.c seemed to be exactly what I wanted:
> > it just trawls /dev for the appropriate major and minor numbers. This
> > code is not performance-critical, so that should be fine. 
> 
> Not true. Even in current state grub-mkconfig is taking considerable
> time to complete on my system with numerous kernels. Unless someone
> implements a cache (it can be invalidated after 5 minutes) not to go
> through the same probing procedure on every grub-probe call I object
> against adding any additional delay in probing procedure

But this code is not called from grub-probe; it is only called from
grub-setup (grep for grub_util_raid_getmembers to confirm for yourself).
A grub-mkconfig run shouldn't go anywhere near this.

-- 
Colin Watson                                       [cjwatson@ubuntu.com]