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Subject: Re: [virtio] [PATCH] ccw: split descriptor/available/used rings
On Tue, 8 Oct 2013 15:26:38 +0300 "Michael S. Tsirkin" <mst@redhat.com> wrote: > On Tue, Oct 08, 2013 at 02:16:06PM +0200, Cornelia Huck wrote: > > On Tue, 8 Oct 2013 15:12:39 +0300 > > "Michael S. Tsirkin" <mst@redhat.com> wrote: > > > > > This reminds me - our use of the SenseID format for device > > > identification is not in the spec, is it? > > > We should probably add it - want to do this? > > > > I don't think there's a need to do so, as it is a standard channel > > command. Every control unit/device since 1973 supports it :) > > The format of the command is standard, yes. > But I really meant which virtio field goes into which field > and how does a driver match. > > Linux guest does: CCW_DEVICE(0x3832, 0) > so it ignores device type and model, and > matches controller model against virtio device ID. > > This really should be documented in spec - it's not good > that people need to look at guest code to write hypervisors. Ah, I see what you mean. It is already there in 2.3.3.1., but we could it more explicit: === SenseID will return the following information for a virtio-ccw proxy device: ---------------------------------------------- | control unit type | 0x3832 | |-----------------------|--------------------| | control unit model | <virtio device id> | |-----------------------|--------------------| | device type | zeroes (unset) | |-----------------------|--------------------| | device model | zeroes (unset) | |-----------------------|--------------------| | extended SenseId data | zeroes (unset) | ---------------------------------------------- A driver for virtio-ccw devices should look for a control unit type of 0x3832 and ignore the device type. === I think ignoring the device type is obvious, though.
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