On 04/28/2013 08:44 PM, Rusty Russell wrote: > "Michael S. Tsirkin" <mst@xxxxxxxxxx> writes: >> > On Wed, Apr 24, 2013 at 09:51:57AM +0300, Pekka Enberg wrote: >>> >> Hi, >>> >> >>> >> On 04/23/2013 12:35 PM, Eric Northup wrote: >>>>> >> >> Do you care about guests with drivers that don't negotiate >>>>> >> >> VIRTIO_NET_F_MRG_RXBUF? >>> >> >>> >> On Wed, Apr 24, 2013 at 5:51 AM, Sasha Levin <sasha.levin@xxxxxxxxxx> wrote: >>>> >> > We usually try to keep backward compatibility, but in this case >>>> >> > mergable RX buffers are about 5 years old now, so it's safe to >>>> >> > assume they'll be running in any guest. >>>> >> > >>>> >> > Unless there is a specific reason to allow working without them >>>> >> > I'd rather keep the code simple in this case. >>> >> >>> >> Are there such guests around? What's the failure scenario for them >>> >> after this patch? >>> >> >>> >> Pekka >> > >> > Warning: have not looked at the patch, just a general comment. >> > >> > I think it's reasonable to assume embedded guests such as PXE won't >> > negotiate any features. And, running old guests is one of the reasons >> > people use virtualization at all. So 5 years is not a lot. >> > >> > In any case, stick to the device spec please, if you want it changed >> > please send a spec patch, don't deviate from it randomly. > Supporting old guests is an quality of implementation issue. It's like > any ABI: if noone will notice, you can remove stuff. > > But the case of "I can receive GSO packets but I don't support mergeable > buffers" is a trivial one: you can "support" it by pretending the guest > can't handle GSO :) > > If you want to support non-Linux guests (eg. bootloaders), you probably > want to keep support for very dumb drivers with no mergable rxbufs > though. Yup, I'm planning on sending a version that supports older guests soonish. Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
