grub booting from virtio but can't see virtio disks

grub booting from virtio but can't see virtio disks

[Martin Kraus]

Hi. I've been wondering why grub can boot from a virtio device but can't see
virtio devices. I wanted to have a generic disk which would have a bios
partition with grub modules and this would include grub.cfg from a second disk.
I could use this image to boot all my virtual linux machines without the need
to have a partition on a logical volume. This way I have a separate virtio
boot lv with partitions and it works fine. It just doesn't seem as nice and I'm
curious if there is a way to get it to work, meaning if for example using efi
or some other kind of bios for qemu or grub module would help it.

thanks
mk

Re: grub booting from virtio but can't see virtio disks

[Gleb Natapov]

On Mon, Aug 02, 2010 at 09:05:48PM +0200, Martin Kraus wrote:
> Hi. I've been wondering why grub can boot from a virtio device but can't see
> virtio devices. I wanted to have a generic disk which would have a bios
> partition with grub modules and this would include grub.cfg from a second disk.
> I could use this image to boot all my virtual linux machines without the need
> to have a partition on a logical volume. This way I have a separate virtio
> boot lv with partitions and it works fine. It just doesn't seem as nice and I'm
> curious if there is a way to get it to work, meaning if for example using efi
> or some other kind of bios for qemu or grub module would help it.
> 
What is your qemu version and qemu command line?

--
			Gleb.

Re: grub booting from virtio but can't see virtio disks

[Martin Kraus]

On Tue, Aug 03, 2010 at 08:58:59AM +0300, Gleb Natapov wrote:
> On Mon, Aug 02, 2010 at 09:05:48PM +0200, Martin Kraus wrote:
> > Hi. I've been wondering why grub can boot from a virtio device but can't see
> > virtio devices. I wanted to have a generic disk which would have a bios
> > partition with grub modules and this would include grub.cfg from a second disk.
> > I could use this image to boot all my virtual linux machines without the need
> > to have a partition on a logical volume. This way I have a separate virtio
> > boot lv with partitions and it works fine. It just doesn't seem as nice and I'm
> > curious if there is a way to get it to work, meaning if for example using efi
> > or some other kind of bios for qemu or grub module would help it.
> > 
> What is your qemu version and qemu command line?

debian squeeze 0.12.4

kvm -cpu host  -drive file=/dev/mapper/virtual-ctech_boot,boot=on,if=virtio,cache=none -drive
file=/dev/mapper/virtual-ctech,if=virtio,cache=none 

virtual-ctech_boot is partitioned and mounts as "/boot" in the virtual guest and virtual-ctech is not
partitioned and is mounted as "/".

This works fine but grub sees only the virtual-ctech_boot from which it is
booting. From that I see it is possible to access virtio devices at boot time but
somehow the bootdisk is different from the other disk. 

I have to set if=ide for virtual-ctech for grub to be able to see it. 

Is it possible to see all the virtio disks in grub or am I just out of luck?

thanks
mk

Re: grub booting from virtio but can't see virtio disks

[Gleb Natapov]

On Sat, Aug 07, 2010 at 05:31:16PM +0200, Martin Kraus wrote:
> On Tue, Aug 03, 2010 at 08:58:59AM +0300, Gleb Natapov wrote:
> > On Mon, Aug 02, 2010 at 09:05:48PM +0200, Martin Kraus wrote:
> > > Hi. I've been wondering why grub can boot from a virtio device but can't see
> > > virtio devices. I wanted to have a generic disk which would have a bios
> > > partition with grub modules and this would include grub.cfg from a second disk.
> > > I could use this image to boot all my virtual linux machines without the need
> > > to have a partition on a logical volume. This way I have a separate virtio
> > > boot lv with partitions and it works fine. It just doesn't seem as nice and I'm
> > > curious if there is a way to get it to work, meaning if for example using efi
> > > or some other kind of bios for qemu or grub module would help it.
> > > 
> > What is your qemu version and qemu command line?
> 
> debian squeeze 0.12.4
> 
> kvm -cpu host  -drive file=/dev/mapper/virtual-ctech_boot,boot=on,if=virtio,cache=none -drive
> file=/dev/mapper/virtual-ctech,if=virtio,cache=none 
> 
> virtual-ctech_boot is partitioned and mounts as "/boot" in the virtual guest and virtual-ctech is not
> partitioned and is mounted as "/".
> 
> This works fine but grub sees only the virtual-ctech_boot from which it is
> booting. From that I see it is possible to access virtio devices at boot time but
> somehow the bootdisk is different from the other disk. 
> 
> I have to set if=ide for virtual-ctech for grub to be able to see it. 
> 
Can you try to use latest seabios and see if it changes something?
You can get seabios here git://git.linuxtogo.org/home/kevin/seabios.gi
To tell qemu to use specific bios image use -bios flag.

> Is it possible to see all the virtio disks in grub or am I just out of luck?
> 
> thanks
> mk

--
			Gleb.

Re: grub booting from virtio but can't see virtio disks

[Martin Kraus]

On Sun, Aug 08, 2010 at 02:39:59PM +0300, Gleb Natapov wrote:
> Can you try to use latest seabios and see if it changes something?
> You can get seabios here git://git.linuxtogo.org/home/kevin/seabios.gi
> To tell qemu to use specific bios image use -bios flag.

This works. I've compiled seabios from git and I can get to the virtio disks.

Thank you for your help. 
mk