[Qemu-devel] Booting from VirtIO disk

[Qemu-devel] Booting from VirtIO disk

[अनुज]

Hi list

I got confused after observing that there is no support for VirtIO
block devices in Seabios supplied with Qemu-0.12.3. But still it can
accept a VirtIO disk as a bootable device and perfectly boots from it.
Then How it's done?

But I can see the VirtIO block device code in Seabios source supplied
with Qemu-0.13.0.

Any pointer or explanation will help.



Thanks & Regards
-- 
Anuj Aggarwal

 .''`.
: :Ⓐ :   # apt-get install hakuna-matata
`. `'`
   `-

Re: [Qemu-devel] Booting from VirtIO disk

[Stefan Hajnoczi]

2010/12/8 अनुज <anuj01@gmail.com>:
> Hi list
>
> I got confused after observing that there is no support for VirtIO
> block devices in Seabios supplied with Qemu-0.12.3. But still it can
> accept a VirtIO disk as a bootable device and perfectly boots from it.
> Then How it's done?
>
> But I can see the VirtIO block device code in Seabios source supplied
> with Qemu-0.13.0.

Before SeaBIOS had native support for virtio-blk there was the extboot
option ROM which could boot from virtio-blk devices by reading a
special I/O port (it does not speak virtio-blk, see qemu-kvm.git
hw/extboot.c).

Stefan

Re: [Qemu-devel] Booting from VirtIO disk

[Stefan Hajnoczi]

2010/12/8 अनुज <anuj01@gmail.com>:
> Hi
>
> thanks for your quick response. Please see the comments inline.
>
> 2010/12/8 Stefan Hajnoczi <stefanha@gmail.com>:
>> 2010/12/8 अनुज <anuj01@gmail.com>:
>>> Hi list
>>>
>>> I got confused after observing that there is no support for VirtIO
>>> block devices in Seabios supplied with Qemu-0.12.3. But still it can
>>> accept a VirtIO disk as a bootable device and perfectly boots from it.
>>> Then How it's done?
>>>
>>> But I can see the VirtIO block device code in Seabios source supplied
>>> with Qemu-0.13.0.
>>
>> Before SeaBIOS had native support for virtio-blk there was the extboot
>> option ROM which could boot from virtio-blk devices by reading a
>> special I/O port (it does not speak virtio-blk, see qemu-kvm.git
>> hw/extboot.c).
>
> I couldn't find this file in qemu versions 0.12.3 and 0.13.0. And my
> same doubt is also for SCSI disks.

Please keep qemu-devel@nongnu.org CCed so others can follow the
conversation and help too.

You probably looked at QEMU source code (from qemu.git).  The extboot
code is in qemu-kvm.git (which is shipped as the "kvm" or "qemu-kvm"
package on distros).  Are you sure you tested virtio-blk boot in
qemu.git-based code?

Stefan

Re: [Qemu-devel] Booting from VirtIO disk

[अनुज]

2010/12/8 Stefan Hajnoczi <stefanha@gmail.com>:
> 2010/12/8 अनुज <anuj01@gmail.com>:
>> Hi
>>
>> thanks for your quick response. Please see the comments inline.
>>
>> 2010/12/8 Stefan Hajnoczi <stefanha@gmail.com>:
>>> 2010/12/8 अनुज <anuj01@gmail.com>:
>>>> Hi list
>>>>
>>>> I got confused after observing that there is no support for VirtIO
>>>> block devices in Seabios supplied with Qemu-0.12.3. But still it can
>>>> accept a VirtIO disk as a bootable device and perfectly boots from it.
>>>> Then How it's done?
>>>>
>>>> But I can see the VirtIO block device code in Seabios source supplied
>>>> with Qemu-0.13.0.
>>>
>>> Before SeaBIOS had native support for virtio-blk there was the extboot
>>> option ROM which could boot from virtio-blk devices by reading a
>>> special I/O port (it does not speak virtio-blk, see qemu-kvm.git
>>> hw/extboot.c).
>>
>> I couldn't find this file in qemu versions 0.12.3 and 0.13.0. And my
>> same doubt is also for SCSI disks.
>
> Please keep qemu-devel@nongnu.org CCed so others can follow the
> conversation and help too.
>
> You probably looked at QEMU source code (from qemu.git).  The extboot
> code is in qemu-kvm.git (which is shipped as the "kvm" or "qemu-kvm"
> package on distros).

Yes I was looking in qemu.git-based code by mistake. I found files in
qemu-kvm.git-based code.

> Are you sure you tested virtio-blk boot in qemu.git-based code?

No I have tested that boot only using qemu-kvm.git-based code.

>
> Stefan
>

Thanks for your help.


Regards
-- 
Anuj Aggarwal

 .''`.
: :Ⓐ :   # apt-get install hakuna-matata
`. `'`
   `-