[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Multiple platform PCI device ID registries?
> -----Original Message----- > From: Ian Campbell > Sent: 13 November 2013 13:14 > To: Paul Durrant > Cc: xen-devel; Ian Jackson; Stefano Stabellini > Subject: Re: Multiple platform PCI device ID registries? > > On Wed, 2013-11-13 at 12:50 +0000, Paul Durrant wrote: > > > -----Original Message----- > > > From: Ian Campbell > > > Sent: 13 November 2013 12:39 > > > To: Paul Durrant > > > Cc: xen-devel; Ian Jackson; Stefano Stabellini > > > Subject: Re: Multiple platform PCI device ID registries? > > > > > > On Wed, 2013-11-13 at 12:30 +0000, Paul Durrant wrote: > > > > > -----Original Message----- > > > > > From: Ian Campbell > > > > > Sent: 13 November 2013 12:09 > > > > > To: Paul Durrant > > > > > Cc: xen-devel; Ian Jackson; Stefano Stabellini > > > > > Subject: Re: Multiple platform PCI device ID registries? > > > > > > > > > > On Wed, 2013-11-13 at 11:58 +0000, Paul Durrant wrote: > > > > > > > > > > > > I'm concerned because that comment refers to XenServer 6.1 but > it > > > now > > > > > > > appears to be being reused as the default device ID for the "Xen > > > > > > > pvdevice". > > > > > > > > > > > > > > Maybe it is safe to reuse this in this way, but the docs should be > > > > > > > updated I think. > > > > > > > > > > > > > > > > > > > I believe it is safe. > > > > > > > > > > How would you describe it in that document? "Xen PV device > (extended > > > > > platform device). Previously used in XenServer 6.1" ? > > > > > > > > > > Is there some spec we can link to regarding how this device should be > > > > > used? > > > > > > ??? > > > > Sorry, missed that. > > You've missed the part about a link to a spec for what the Xen PV device > is, when it should appear, how it relates to the platform device again Oh sorry - too many emails in different threads... No, there is no spec. in existence. The xl.cfg manpage refers readers to pci-device-reservations.txt so I guess that would be the best place to add some words. > > > No, it wasn't previously used in 6.1 because it's not really the same > > (as the pv device doesn't implement the fixed IO ports). I also don't > > want to confuse it with the platform device, for that reason. It is a > > new distinct and I agree that the fact it defaults to device ID is > > confusing although it's safe - I will therefore submit a patch to QEMU > > to modify it as I suggested before, so that the id *must* be specified > > by the toolstack. > > Ack. > > > > > > > Best bet is to just document "Don't Do That Then". Is there some > > > XenServer way we can tell people to fix this (by changing the ID back?) > > > > > > > Well part of the problem is that we don't support use of PVonHVM linux > > in XenServer at all! The best thing is probably to tackle this on the > > XenServer forums if and when someone posts the problem there. Adding > > the extra blacklisting code to XenServer's QEMU and then getting that > > into a hotfix should hopefully avoid future problems too - although we > > may get 'why are my PV frontends not working?'-type questions. > > Ah, I see now why it is a XS side fix. > > > > I think "no platform device and no pv device" is a valid and useful > > > configuration, meaning "use emulated devices". "no platform device, yes > > > pv device" is the one to avoid. > > > > > > > Hmm. How about splitting out the fixed IO ports then? That way the > > platform device could be safely turned off if the PV device was > > present. It seems like a cleaner and safer thing to do. > > I thought when the PV device was added it was agreed that it would only > ever be as an extension to the platform device, not a replacement for > it. > > Otherwise you get into situations where cloud providers need to know > which to provide, whereas with a baseline platform device always there > things can try and work. > Yes, agreed, it is intended as an extra device but the fact that removing the *PCI* platform device from the VM disables the fixed IO ports is somewhat counter-intuitive so I was proposing that should be fixed. Then *if* someone had the PV device and removed the platform device any bound PV frontends would continue to function. Paul _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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