Re: [Xen-users] Xen domU cannot boot via PV-GRUB

["Fajar A. Nugraha" <list@xxxxxxxxx>]

On Fri, Jan 14, 2011 at 7:44 AM, GNUbie <gnubie@xxxxxxxxx> wrote:
> Hello Fajar,
>
> On Fri, Jan 14, 2011 at 6:04 AM, Fajar A. Nugraha <list@xxxxxxxxx> wrote:
>>
>> I assume you ACTUALLY have the correct partition/LV with LABEL=/ on
>> domU's disk image?
>
> Yes. But as I've said, I also tried using /dev/sda2 and /dev/xvda2 but
> with no luck.

That's not what I asked.

The key point is you need to have correct root. If you actually create
the filesystem with "mkfs.ext3 -L /" or run "e2label ...", then the
label should be there, and you don't need to worry (on grub.conf
anyway) whether it's hda2, sda2, or xvda2.

On the other hand, if you create the image from scratch, and did NOT
create the label manually, and transfer the files using
rsync/tar/whatever, you will not have the label.

>
>>
>>> Loading xen-blkfront.ko module
>>> [    0.456365] blkfront device/vbd/2050 num-ring-pages 1 nr_ents 32.
>>> [    0.460302] blkfront device/vbd/2064 num-ring-pages 1 nr_ents 32.
>>> [    0.484444] blkfront device/vbd/2051 num-ring-pages 1 nr_ents 32.
>>> [    0.487167] blkfront: regular deviceid=0x802 major,minor=8,2,
>>> assuming parts/disk=16
>>> [    0.488610] blkfront: regular deviceid=0x810 major,minor=8,16,
>>> assuming parts/disk=16
>>> [    0.488850]  xvdb: unknown partition table
>>> [    0.559870] blkfront: regular deviceid=0x803 major,minor=8,3,
>>> assuming parts/disk=16
>>
>> You should see the disks and detected partition tables on boot. Your
>> log only xvdb is detected with "unknown partition table", which is
>> weird. Does the disk image actually HAVE partition on it, or do you
>> create a filesystem directly on that image? What does your domU config
>> file looks like? What does "fdisk -l /path/to/your/disk-image" look
>> like?
>
> This system (domU) used to be in another dom0 that uses /dev/xvd*
> partitions then I dump'ed and restore'd a copy of this system to this
> new dom0 that uses /dev/sd* partitions.

again, I didn't ask that, and it's not relevant really.
I asked

>> What does your domU config
>> file looks like?

... to know how you map the disk from your config file. For example,
in my system:

disk =  [
        'tap:aio:/z/rhel6/xvda.img,xvda,w',
        ]

means I map the disk as xvda. Your log is weird, in that it shows 3
block devices detected, but only "xvdb" shown. The config file might
provide some information as to why it happens.

I also asked

>> What does "fdisk -l /path/to/your/disk-image" look like

... cause it might be that you simply don't have a parition at all. Or
your root is on LVM, not a partition. Mine shows something like this

# fdisk -l /z/rhel6/xvda.img
last_lba(): I don't know how to handle files with mode 81a4
You must set cylinders.
You can do this from the extra functions menu.

Disk /z/rhel6/xvda.img: 0 MB, 0 bytes
255 heads, 63 sectors/track, 0 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

            Device Boot      Start         End      Blocks   Id  System
/z/rhel6/xvda.img1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/z/rhel6/xvda.img2              64        1306     9972736   8e  Linux LVM
Partition 2 has different physical/logical endings:
     phys=(1023, 254, 63) logical=(1305, 106, 17)

... which shows I use LVM, and "/" is located in LVM (cause first
partition is too small to be "/")

>
> I remember that the original partitions of this domU from its original
> dom0 were:
>
>  202        1   10240001 xvda1 => /
>  202        2  356485632 xvda2 => /data
>  202        3     917504 xvda3 => swap
>
> But even from the original dom0, the domU do not have a /dev/xvdb partition.

I didn't ask how it was on the original dom0. I asked what your
current image has right now.

If you simply copy the image then the partition might be the same, but
in that case you've made an obvious mistake: your "/" was on xvda1.
Passing "root=/dev/sda2" is simply silly.

It's useless to go into details right now without knowing what your
current image looks like.

>
> Going back to your question. I don't remember creating the /dev/xvdb
> partition and it doesn't have an /dev/xvdb partition.

I didn't ask whether you create it or not.
I asked what your domU config looks like, and what fdisk output on
your current image looks like.

If you don't answer it then there's nothing I can do to help.

-- 
Fajar

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