Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: "liang yan" <lyan@suse.com>,
	Jailhouse <jailhouse-dev@googlegroups.com>,
	"Daniel P. Berrangé" <berrange@redhat.com>,
	"Claudio Fontana" <claudio.fontana@gmail.com>,
	qemu-devel <qemu-devel@nongnu.org>,
	"Markus Armbruster" <armbru@redhat.com>,
	"Hannes Reinecke" <hare@suse.de>,
	"Stefan Hajnoczi" <stefanha@redhat.com>
Subject: Re: [RFC][PATCH 2/3] docs/specs: Add specification of ivshmem device revision 2
Date: Tue, 12 Nov 2019 03:04:13 -0500	[thread overview]
Message-ID: <20191112024400-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <ef21ed49-d315-4ee5-716b-096d8af1d79c@siemens.com>

On Mon, Nov 11, 2019 at 05:38:29PM +0100, Jan Kiszka wrote:
> On 11.11.19 17:11, Michael S. Tsirkin wrote:
> > On Mon, Nov 11, 2019 at 03:27:43PM +0000, 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.
> > 
> > Well we do have:
> > 
> > 	B.3
> > 	What Device Number?
> > 	Device numbers can be reserved by the OASIS committee: email virtio-dev@lists.oasis-open.org to secure
> > 	a unique one.
> > 	Meanwhile for experimental drivers, use 65535 and work backwards.
> > 
> > So it seems it can  in theory conflict at least with experimental virtio devices.
> > 
> > Really it's messy that people are reusing the virtio vendor ID for
> > random stuff - getting a vendor ID is only hard for a hobbyist, any big
> > company already has an ID - but if it is a hobbyist and they at least
> > register then doesn't cause much harm.
> 
> Note that ivshmem came from a research environment. I do know if there was a
> check for the IDs at the point the code was merged.
> 
> That said, I may get a device ID here as well, provided I can explain that
> not a single "product" will own it, but rather an open specification.
> 
> Jan

OK, up to you - if you decide you want an ID reserved, pls let us know.

At this point I'm not sure I have a good grasp which IDs are
registered where anymore. If someone can write it up, that would
be great too!

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