Re: SeaBIOS and GRUB booting from Virtio devices [was: GRUB and support for Virtio]

[Daniel Bareiro <daniel-listas@gmx.net>]

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On Tuesday, 24 August 2010 11:23:59 -0300,
Daniel Bareiro wrote:

> > Strange, i did 2 clean installs of centos 5.5 on an ubuntu 9.10 host
> > and it went flawless with virtio devices ( both disks and network ).

> Doing some tests with CentOS 5.5 on a KVM virtual machine, after doing
> the installation, I added a second disk. But when trying to boot from
> it, I get the following error:
> 
> ---------------------------------------------------------------------
> root (hd1,0)
> 
> Error 21: Selected disk does not exist
> ---------------------------------------------------------------------
> 
> 
> The two disks are Virtio devices that are recognized when booting from
> the first disk:
> 
> ---------------------------------------------------------------------
> [root@localhost ~]# fdisk -l /dev/vda
> 
> Disco /dev/vda: 10.7 GB, 10737418240 bytes
> 255 heads, 63 sectors/track, 1305 cylinders
> Unidades = cilindros de 16065 * 512 = 8225280 bytes
> 
> Disposit. Inicio    Comienzo      Fin      Bloques  Id  Sistema
> /dev/vda1   *           1        1174     9430123+  fd  Linux raid autodetect
> /dev/vda2            1175        1305     1052257+  fd  Linux raid autodetect
> [root@localhost ~]#
> [root@localhost ~]#
> [root@localhost ~]# fdisk -l /dev/vdb
> 
> Disco /dev/vdb: 10.7 GB, 10737418240 bytes
> 255 heads, 63 sectors/track, 1305 cylinders
> Unidades = cilindros de 16065 * 512 = 8225280 bytes
> 
> Disposit. Inicio    Comienzo      Fin      Bloques  Id  Sistema
> /dev/vdb1   *           1        1174     9430123+  fd  Linux raid autodetect
> /dev/vdb2            1175        1305     1052257+  fd  Linux raid autodetect
> ---------------------------------------------------------------------
> 
> The idea of these tests is to set up software RAID1 on a running
> system, since, it seems that Anaconda does not support installation on
> degraded RAID.
> 
> But I'm not sure if this is a problem of Virtio or that GRUB is not
> recognizing the second disk.
> 
> I made sure to modify /boot/grub/device.map with the entry for the new
> disk:
> 
> ---------------------------------------------------------------------
> [root@localhost grub]# cat /boot/grub/device.map
> # this device map was generated by anaconda
> (hd0)     /dev/vda
> (hd1)     /dev/vdb
> ---------------------------------------------------------------------
> 
> And the reconfiguration of GRUB on both disks did not give problems:
> 
> ---------------------------------------------------------------------
> [root@localhost grub]# grub --device-map=/boot/grub/device.map
> 
> 
>     GNU GRUB  version 0.97  (640K lower / 3072K upper memory)
> 
>  [ Minimal BASH-like line editing is supported.  For the first word, TAB
>    lists possible command completions.  Anywhere else TAB lists the
> possible
>    completions of a device/filename.]
> grub> root (hd0,0)
> root (hd0,0)
>  Filesystem type is ext2fs, partition type 0xfd
> grub> setup (hd0)
> setup (hd0)
>  Checking if "/boot/grub/stage1" exists... yes
>  Checking if "/boot/grub/stage2" exists... yes
>  Checking if "/boot/grub/e2fs_stage1_5" exists... yes
>  Running "embed /boot/grub/e2fs_stage1_5 (hd0)"...  15 sectors are
> embedded.
> succeeded
>  Running "install /boot/grub/stage1 (hd0) (hd0)1+15 p
> (hd0,0)/boot/grub/stage2 /boot/grub/grub.conf"... succeeded
> Done.
> grub> root (hd1,0)
> root (hd1,0)
>  Filesystem type is ext2fs, partition type 0xfd
> grub> setup (hd1)
> setup (hd1)
>  Checking if "/boot/grub/stage1" exists... yes
>  Checking if "/boot/grub/stage2" exists... yes
>  Checking if "/boot/grub/e2fs_stage1_5" exists... yes
>  Running "embed /boot/grub/e2fs_stage1_5 (hd1)"...  15 sectors are
> embedded.
> succeeded
>  Running "install /boot/grub/stage1 (hd1) (hd1)1+15 p
> (hd1,0)/boot/grub/stage2 /boot/grub/grub.conf"... succeeded
> Done.
> grub> quit
> quit
> ---------------------------------------------------------------------
> 
> 
> Any idea what may be causing the problem?

Martin Kraus seems that recently experienced a similar problem and this
was linked to SeaBIOS [1] and compiling the version from the git would
solve this problem. I had no problems with GRUB trying to boot from two
different IDE drives. 

I would like to know if there are plans to incorporate this to stable
KVM in the short term.

Regards,
Daniel

[1] http://www.spinics.net/lists/kvm/msg39928.html
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