[gentoo-user] Gentoo as kvm guest with virtio

[gentoo-user] Gentoo as kvm guest with virtio

[hw]

Hi,

what is required to boot Gentoo as a kvm guest with
virtio devices?

I'm stuck with 'Could not find the root block device
in UUID= ...' when trying to boot the guest.

Is grub2 unable to work with virtio devices?

Re: [gentoo-user] Gentoo as kvm guest with virtio

[Rich Freeman]

On Wed, Mar 9, 2016 at 12:41 PM, hw <hw@gc-24.de> wrote:
>
> I'm stuck with 'Could not find the root block device
> in UUID= ...' when trying to boot the guest.
>
> Is grub2 unable to work with virtio devices?
>

Are you sure that is a grub2 message?  It seems more likely that this
is a message from the kernel (unless it is referring to the grub2 root
- posting the entire error would probably help here, and I didn't
realize grub2 even can find its root with a UUID assuming it actually
can).  Does your kernel have virtio support enabled?  What initramfs
are you using?  The problem could lie with either.  See if you can get
the initramfs to give you a shell (usually this can be done with a
kernel command line option) and see what block devices it can see (run
blkid or such).

If you're not using an initramfs then that is your problem.  You can't
use UUID to reference your root if you aren't using an initramfs.

-- 
Rich

Re: [gentoo-user] Gentoo as kvm guest with virtio

[Bill Kenworthy]

On 10/03/16 01:56, Rich Freeman wrote:
> On Wed, Mar 9, 2016 at 12:41 PM, hw <hw@gc-24.de> wrote:
>>
>> I'm stuck with 'Could not find the root block device
>> in UUID= ...' when trying to boot the guest.
>>
>> Is grub2 unable to work with virtio devices?
>>
> 
> Are you sure that is a grub2 message?  It seems more likely that this
> is a message from the kernel (unless it is referring to the grub2 root
> - posting the entire error would probably help here, and I didn't
> realize grub2 even can find its root with a UUID assuming it actually
> can).  Does your kernel have virtio support enabled?  What initramfs
> are you using?  The problem could lie with either.  See if you can get
> the initramfs to give you a shell (usually this can be done with a
> kernel command line option) and see what block devices it can see (run
> blkid or such).
> 
> If you're not using an initramfs then that is your problem.  You can't
> use UUID to reference your root if you aren't using an initramfs.
> 

I had to use this on grub install:

grub2-install --target=i386-pc /dev/vda && \
grub2-mkconfig -o /boot/grub/grub.cfg

It couldn't find the right module without the hint.

BillK

Re: [gentoo-user] Gentoo as kvm guest with virtio

[hw]

Rich Freeman wrote:
> On Wed, Mar 9, 2016 at 12:41 PM, hw <hw@gc-24.de> wrote:
>>
>> I'm stuck with 'Could not find the root block device
>> in UUID= ...' when trying to boot the guest.
>>
>> Is grub2 unable to work with virtio devices?
>>
>
> Are you sure that is a grub2 message?  It seems more likely that this
> is a message from the kernel (unless it is referring to the grub2 root
> - posting the entire error would probably help here, and I didn't
> realize grub2 even can find its root with a UUID assuming it actually
> can).  Does your kernel have virtio support enabled?  What initramfs
> are you using?  The problem could lie with either.  See if you can get
> the initramfs to give you a shell (usually this can be done with a
> kernel command line option) and see what block devices it can see (run
> blkid or such).

I think it is a message from the kernel, so I'm trying to figure out
which drivers need to be enabled for the kernel to see the virtio-disk.
There doesn't seem to be any information at all about what is needed.

 > If you're not using an initramfs then that is your problem.  You can't
 > use UUID to reference your root if you aren't using an initramfs.

I'm using one, though I'm compiling most/all of what I know that will be
needed in rather than using modules.  Something must still be missing,
and I don't what.  At least now I know that the kernel is missing
something.

Re: [gentoo-user] Gentoo as kvm guest with virtio

[hw]

Bill Kenworthy wrote:
> On 10/03/16 01:56, Rich Freeman wrote:
>> On Wed, Mar 9, 2016 at 12:41 PM, hw <hw@gc-24.de> wrote:
>>>
>>> I'm stuck with 'Could not find the root block device
>>> in UUID= ...' when trying to boot the guest.
>>>
>>> Is grub2 unable to work with virtio devices?
>>>
>>
>> Are you sure that is a grub2 message?  It seems more likely that this
>> is a message from the kernel (unless it is referring to the grub2 root
>> - posting the entire error would probably help here, and I didn't
>> realize grub2 even can find its root with a UUID assuming it actually
>> can).  Does your kernel have virtio support enabled?  What initramfs
>> are you using?  The problem could lie with either.  See if you can get
>> the initramfs to give you a shell (usually this can be done with a
>> kernel command line option) and see what block devices it can see (run
>> blkid or such).
>>
>> If you're not using an initramfs then that is your problem.  You can't
>> use UUID to reference your root if you aren't using an initramfs.
>>
>
> I had to use this on grub install:
>
> grub2-install --target=i386-pc /dev/vda && \
> grub2-mkconfig -o /boot/grub/grub.cfg
>
> It couldn't find the right module without the hint.

That seems to work just fine:


livecd linux # grub2-install /dev/vda
Installing for i386-pc platform.
installation beendet. Keine Fehler aufgetreten.


Do you think it claims to have worked but actually didn't?

Re: [gentoo-user] Gentoo as kvm guest with virtio

[Rich Freeman]

On Thu, Mar 10, 2016 at 6:10 AM, hw <hw@gc-24.de> wrote:
>
> livecd linux # grub2-install /dev/vda
> Installing for i386-pc platform.
> installation beendet. Keine Fehler aufgetreten.
>
> Do you think it claims to have worked but actually didn't?
>

You wouldn't be getting kernel errors if there was a grub problem.
Grub is long gone by the time the kernel starts producing output.


-- 
Rich

[gentoo-user] SOLVED: Gentoo as kvm guest with virtio not detecting vda device (Gentoo as kvm guest with virtio)

[hw]

Hi,

I found that I needed to enable VIRTIO_PCI_LEGACY for the guest kernel.
I've also set 'virtio_pci.force_legacy=1' as kernel command line option.

This was suggested here: https://bugs.archlinux.org/task/44573


hw wrote:
> Bill Kenworthy wrote:
>> On 10/03/16 01:56, Rich Freeman wrote:
>>> On Wed, Mar 9, 2016 at 12:41 PM, hw <hw@gc-24.de> wrote:
>>>>
>>>> I'm stuck with 'Could not find the root block device
>>>> in UUID= ...' when trying to boot the guest.
>>>>
>>>> Is grub2 unable to work with virtio devices?
>>>>
>>>
>>> Are you sure that is a grub2 message?  It seems more likely that this
>>> is a message from the kernel (unless it is referring to the grub2 root
>>> - posting the entire error would probably help here, and I didn't
>>> realize grub2 even can find its root with a UUID assuming it actually
>>> can).  Does your kernel have virtio support enabled?  What initramfs
>>> are you using?  The problem could lie with either.  See if you can get
>>> the initramfs to give you a shell (usually this can be done with a
>>> kernel command line option) and see what block devices it can see (run
>>> blkid or such).
>>>
>>> If you're not using an initramfs then that is your problem.  You can't
>>> use UUID to reference your root if you aren't using an initramfs.
>>>
>>
>> I had to use this on grub install:
>>
>> grub2-install --target=i386-pc /dev/vda && \
>> grub2-mkconfig -o /boot/grub/grub.cfg
>>
>> It couldn't find the right module without the hint.
>
> That seems to work just fine:
>
>
> livecd linux # grub2-install /dev/vda
> Installing for i386-pc platform.
> installation beendet. Keine Fehler aufgetreten.
>
>
> Do you think it claims to have worked but actually didn't?
>
>