On Fri, Apr 20, 2018 at 8:28 AM, Michael S. Tsirkin <m...@redhat.com> wrote: > On Fri, Apr 20, 2018 at 07:56:14AM -0700, Alexander Duyck wrote: >> > I think for virtio it should include the feature bit, yes. >> > Adding feature bit is very easy - post a patch to the virtio TC mailing >> > list, wait about a week to give people time to respond (two weeks if it >> > is around holidays and such). >> >> The problem is we are talking about hardware/FPGA, not software. >> Adding a feature bit means going back and updating RTL. The software >> side of things is easy, re-validating things after a hardware/FPGA >> change not so much. >> >> If this is a hard requirement I may just drop the virtio patch, push >> what I have, and leave it to Mark/Dan to deal with the necessary RTL >> and code changes needed to support Virtio as I don't expect the >> turnaround to be as easy as just a patch. >> >> Thanks. >> >> - Alex > > Let's focus on virtio in this thread.
That is kind of what I was thinking, and why I was thinking it might make sense to make the virtio specific changes a separate patch set. I could get the PCI bits taken care of in the meantime since they effect genetic PCI, NVMe, and the Amazon ENA interfaces. > Involving the virtio TC in host/guest interface changes is a > hard requirement. It's just too easy to create conflicts otherwise. > > So you guys should have just sent the proposal to the TC when you > were doing your RTL and you would have been in the clear. Agreed. I believe I brought this up when I was originally asked to look into the coding for this. > Generally adding a feature bit with any extension is a good idea: > this way you merely reserve a feature bit for your feature through > the TC and are more or less sure of forward and backward compatibility. > It's incredibly easy. Agreed, though in this case I am not sure it makes sense since this isn't necessarily something that is a Virtio feature itself. It is just a side effect of the fact that they are adding SR-IOV support to a device that happens to emulate Virtio NET and apparently their PF has to be identical to the VF other than the PCIe extended config space. > But maybe it's not needed here. I am not making the decisions myself. > Not too late: post to the TC list and let's see what the response is. > Without a feature bit you are making a change affecting all future > implementations without exception so the bar is a bit higher: you need > to actually post a spec text proposal not just a patch showing how to > use the feature, and TC needs to vote on it. Voting takes a week, > review a week or two depending on change complexity. > > Hope this helps, > > -- > MST I think I will leave this for Dan and Mark to handle since I am still not all that familiar with the hardware in use here. Once a decision has been made him and Mark could look at pushing either the one line patch or something more complex involving a feature flag. Thanks. Alex
