Re: [Qemu-devel] virtio block device and sysfs

[Marc Haber]

Hi,

On Tue, Mar 09, 2010 at 03:34:07PM -0600, Anthony Liguori wrote:
> On 03/06/2010 04:42 PM, Marc Haber wrote:
>> My goal is to have a possibility to give a "speaking" name to any
>> block device handed into a guest instance by the host. That name
>> should be visible inside the guest, just as a LV is visible with its
>> name in the system running the LVM.
>>
>> For example I would like to say on the qemu or kvm command line
>> '-drive file=some-file,label=some-label,if=virtio', and have the
>> string "some-label" show up somewhere in /sys/block in the guest, much
>> as /sys/block/sda/device/model shows the hardware vendor and type for
>> a standard SATA disk. The guest could then handle the information
>> passed into it by the host with udev rules, allowing fstab constructs
>> like "mount /dev/virtio/block/by-label/some-label as /usr"
>>    
>
> You probably would just want to plumb ,serial=X into the virtio-blk  
> config space and have the driver use it.  Then you can do  
> /dev/block/by-id/XXXXX

It the serial "number" can be alphanumeric, that would be great to have.

> John attempted this and it was reverted because the implementation  
> exhausted the PCI config space.

I don't understand that. Existig hardware devices dump much more of
their data such as vendor and model type information into the config
space, how can using a field that real hardware uses exhaust the
config space?

Greetings
Marc

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