"Michael S. Tsirkin" <m...@redhat.com> 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.le...@oracle.com> 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. Cheers, Rusty. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
