On Mon, Oct 19, 2009 at 3:31 PM, Tomasz Chmielewski <[email protected]> wrote:
> Luca Tettamanti wrote:
>>
>> On Mon, Oct 19, 2009 at 2:14 PM, Tomasz Chmielewski <[email protected]>
>> wrote:
>>>
>>> lspci implies that the virtio block device is a "SCSI storage
>>> controller",
>>> i.e.:
>>>
>>> 00:05.0 SCSI storage controller: Qumranet, Inc. Virtio block device
>>>
>>>
>>> However, virtio block devide does not have much to do with SCSI (in
>>> sense:
>>> sdparm does not think it is a SCSI device; virtio_blk does not depend on
>>> any
>>> SCSI moduled like sd_mod).
>>>
>>> Is "SCSI storage controller" a proper description for this device?
>>
>> It does not talk SCSI protocol if that's what you're asking. The
>> description you see comes from the PCI class (storage controller) and
>> subclass (SCSI controller); the meaning of the class/subclass is fixed
>> by the PCI standard.
>
> So why was "SCSI storage controller" any better than "IDE interface" or
> "SATA controller" for virtio block device, if it does not talk SCSI protocol
> (other than "SCSI storage controller" being the first on the list of
> subclasses)?
Because both ATA and SATA classes have a generic driver that would try
to bind to that controller (and the whole point of virtio block device
is to avoid emulating a ATA/SATA controller).
> Doesn't "80 Mass storage controller" ("0x80 0x00 Other mass storage
> controller") fit better for virtio block device?
Maybe. I guess that are compatibility problem with "other" operating systems.
Luca
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