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Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device rev
From: |
Michael S. Tsirkin |
Subject: |
Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2 |
Date: |
Mon, 11 Nov 2019 11:14:49 -0500 |
On Mon, Nov 11, 2019 at 04:42:52PM +0100, Jan Kiszka wrote:
> On 11.11.19 16:27, Daniel P. Berrangé wrote:
> > On Mon, Nov 11, 2019 at 10:08:20AM -0500, Michael S. Tsirkin wrote:
> > > On Mon, Nov 11, 2019 at 02:59:07PM +0100, Jan Kiszka wrote:
> > > > On 11.11.19 14:45, Michael S. Tsirkin wrote:
> > > > > On Mon, Nov 11, 2019 at 01:57:11PM +0100, Jan Kiszka wrote:
> > > > > > +| Offset | Register | Content
> > > > > > |
> > > > > > +|-------:|:-----------------------|:-----------------------------------------------------|
> > > > > > +| 00h | Vendor ID | 1AF4h
> > > > > > |
> > > > > > +| 02h | Device ID | 1110h
> > > > > > |
> > > > >
> > > > > Given it's a virtio vendor ID, please reserve a device ID
> > > > > with the virtio TC.
> > > >
> > > > Yeah, QEMU's IVSHMEM was always using that. I'm happy to make this
> > > > finally
> > > > official.
> > > >
> > >
> > > And I guess we will just mark it reserved or something right?
> > > Since at least IVSHMEM 1 isn't a virtio device.
> > > And will you be reusing same ID for IVSHMEM 2 or a new one?
> >
> > 1110h isn't under either of the virtio PCI device ID allowed ranges
> > according to the spec:
> >
> > "Any PCI device with PCI Vendor ID 0x1AF4, and PCI Device
> > ID 0x1000 through 0x107F inclusive is a virtio device.
> > ...
> > Additionally, devices MAY utilize a Transitional PCI Device
> > ID range, 0x1000 to 0x103F depending on the device type. "
> >
> > So there's no need to reserve 0x1110h from the virtio spec POV.
>
> Indeed.
>
> >
> > I have, however, ensured it is assigned to ivshmem from POV of
> > Red Hat's own internal tracking of allocated device IDs, under
> > its vendor ID.
> >
> > If ivshmem 2 is now a virtio device, then it is a good thing that
> > it will get a new/different PCI device ID, to show that it is not
> > compatible with the old device impl.
>
> At this stage, it is just a PCI device that may be used in combination with
> virtio (stacked on top), but it is not designed like a normal virtio (PCI)
> device. That's because it lacks many properties of regular virtio devices,
> like queues.
>
> So, if such a device could be come part of the virtio spec, it would be
> separate from the rest, and having an ID from the regular range would likely
> not be helpful in this regard.
>
> Jan
I agree it needs a separate ID not from the regular range.
It's a distinct transport.
Maybe even a distinct vendor ID - we could easily get another one
if needed.
> --
> Siemens AG, Corporate Technology, CT RDA IOT SES-DE
> Corporate Competence Center Embedded Linux
- [RFC][PATCH 0/3] IVSHMEM version 2 device for QEMU, Jan Kiszka, 2019/11/11
- [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Jan Kiszka, 2019/11/11
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Michael S. Tsirkin, 2019/11/11
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Jan Kiszka, 2019/11/11
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Michael S. Tsirkin, 2019/11/11
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Daniel P . Berrangé, 2019/11/11
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Jan Kiszka, 2019/11/11
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2,
Michael S. Tsirkin <=
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Jan Kiszka, 2019/11/11
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Michael S. Tsirkin, 2019/11/11
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Jan Kiszka, 2019/11/11
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Michael S. Tsirkin, 2019/11/12
- Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2, Jan Kiszka, 2019/11/20
[RFC][PATCH 3/3] contrib: Add server for ivshmem revision 2, Jan Kiszka, 2019/11/11
[RFC][PATCH 1/3] hw/misc: Add implementation of ivshmem revision 2 device, Jan Kiszka, 2019/11/11
Re: [RFC][PATCH 0/3] IVSHMEM version 2 device for QEMU, no-reply, 2019/11/11
Re: [RFC][PATCH 0/3] IVSHMEM version 2 device for QEMU, Liang Yan, 2019/11/27