Re: [Qemu-devel] virtio-blk-pci: how to tell if it is CD or HDD?

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 10/16/2013 05:36 PM, Paolo Bonzini wrote:
> Il 16/10/2013 07:04, Alexey Kardashevskiy ha scritto:
>> Hi!
>>
>> Normally on sPAPR platform the IBMVSCSI host bus adapter is used which is
>> SCSI. So when we want some image to appear as a DVD to the guest
>> (particularly SLOF - our firmware), we use "-device scsi-cd". Or QEMU
>> extracts this automatically from the "media=cdrom" property of "-drive"
>> (correct?). And then the SCSI bus tells the guest what is what. SLOF
>> firmware uses this to create "disk" and "cdrom" aliases to correcly apply
>> the boot order. So far so good.
>>
>> Now we are trying (via libvirt) to add both HDD and DVD as "virtio-blk-pci"
>> devices:
>>
>> -drive file=virtimg/rhel6-root.img,if=none,format=raw,\
>> id=drive-virtio-disk1,cache=none \
>> -device virtio-blk-pci,bus=pci,addr=0x4,\
>> drive=drive-virtio-disk1,id=virtio-disk1,bootindex=2 \
>> \
>> -drive file=virtimg/SLES-11-SP3-DVD-ppc64-GM-DVD1.iso,\
>> if=none,media=cdrom,id=drive-virtio-disk2,readonly=on,\
>> format=raw\
>> -device virtio-blk-pci,bus=pci,addr=0x5,\
>> drive=drive-virtio-disk2,id=virtio-disk2,bootindex=1
>>
>> No SCSI bus is created in this case. Both devices appear to SLOF as HDDs so
>> it creates just one "disk" alias and no "cdrom" alias and if we are not
>> lucky and DVD got bigger PCI slot#, we will never be able to boot from DVD.
>>
>> Is there any way to distinguish HDD from DVD via virtio protocol from the
>> guest (i.e. SLOF)? Thanks!
> 
> No, virtio-blk is always a HDD.

Thanks, good to know.

> Does bootindex work with pSeries?

Nope. Seems the time to support this has come :)



> 
> Paolo
> 


-- 
Alexey