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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Mon, 13 Jan 2014 11:13:07 +0100
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Subject: Re: [Qemu-devel] [PATCH] Docs: Introduce multiport serial support
 in qemupciserial.inf
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>, Yan Vugenfirer <yvugenfi@redhat.com>, qemu-devel list <qemu-devel@nongnu.org>, Ronen Hod <rhod@redhat.com>, Anthony Liguori <aliguori@amazon.com>, Dmitry Fleytman <dfleytma@redhat.com>, Miki Mishael <mmishael@redhat.com>

On Mi, 2014-01-08 at 17:11 +0100, Paolo Bonzini wrote:
> Il 08/01/2014 16:07, Yan Vugenfirer ha scritto:
> >>>
> >>> +%QEMU-PCI_SERIAL_1_PORT%=ComPort_inst1,
> >>> PCI\VEN_1B36&DEV_0002&SUBSYS_11001AF4&REV_01
> >>> +%QEMU-PCI_SERIAL_2_PORT%=ComPort_inst2,
> >>> PCI\VEN_1B36&DEV_0003&SUBSYS_11001AF4&REV_01
> >>> +%QEMU-PCI_SERIAL_4_PORT%=ComPort_inst4,
> >>> PCI\VEN_1B36&DEV_0004&SUBSYS_11001AF4&REV_01
> >>
> >> I think checking the subsystem is not necessary (and I think downstreams
> >> could legitimately change it).  Can you check CC and REV but not SUBSYS?
> > 
> > PNP ID can be reduced to vendor and device ID only, for example:
> > PCI\VEN_1B36&DEV_0002 . But in this case we cannot check revision.
> 
> Gerd, Michael, what do you think is better?  Not check revision, or
> enforcing subsystem?

No need to check the revision.  There is only one, I doubt this will
ever change, and should we do a rev2 virtual hardware it is supposed to
be backward-compatible to rev1 (otherwise we should hand out a new pci
id to the device).

[ drivers which depend on few features of the hypothetical rev2 hardware
  and don't work with rev1 would need a revision check ]

cheers,
  Gerd