Linux Virtualization - Jun 2013 - what should a virtio-mmio transport without a backend look like?

On 21 June 2013 17:47, Pawel Moll <pawel.moll at arm.com>
wrote:
> On Fri, 2013-06-21 at 17:41 +0100, Peter Maydell wrote:
>> As it happens, if you use the command line to specify
>> a virtio device it doesn't make the same complaint about
>> bad magic number as if you specify it via dtb, but that
>> should probably be fixed in the kernel :-)
>
> I don't really see how this would be possible - the "complaining
code"
> is just a normal platform device probe function.
Sorry, you're correct and I misremembered. I just retested
with specifying via command line and it behaves the same
way as via dtb.

-- PMM

Hi Peter,

On 06/21/2013 01:01 PM, Peter Maydell wrote:
> On 21 June 2013 17:47, Pawel Moll <pawel.moll at arm.com> wrote:
>> On Fri, 2013-06-21 at 17:41 +0100, Peter Maydell wrote:
>>> As it happens, if you use the command line to specify
>>> a virtio device it doesn't make the same complaint about
>>> bad magic number as if you specify it via dtb, but that
>>> should probably be fixed in the kernel :-)
>>
>> I don't really see how this would be possible - the
"complaining code"
>> is just a normal platform device probe function.
> 
> Sorry, you're correct and I misremembered. I just retested
> with specifying via command line and it behaves the same
> way as via dtb.
I was going to say something. I see that complaint all the time.

Anyhow, I just did a quick experiment with 0-size block devices, and they seem
to work for me, although trying to mount the device yields the confusing
message, "mount: mounting /dev/vda on mount failed: Invalid argument".

Regards,
Christopher

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by the Linux Foundation.

On 21 June 2013 19:01, Christopher Covington <cov at codeaurora.org>
wrote:
> Anyhow, I just did a quick experiment with 0-size block devices, and they
seem
> to work for me, although trying to mount the device yields the confusing
> message, "mount: mounting /dev/vda on mount failed: Invalid
argument".
I'm confused -- what's the significance of zero size
block devices?

thanks
-- PMM