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Tsirkin" To: Alvaro Karsz Cc: Jason Wang , "davem@davemloft.net" , "edumazet@google.com" , "kuba@kernel.org" , "pabeni@redhat.com" , "virtualization@lists.linux-foundation.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH net] virtio-net: reject small vring sizes Message-ID: <20230417073830-mutt-send-email-mst@kernel.org> References: <20230416164453-mutt-send-email-mst@kernel.org> <20230417021725-mutt-send-email-mst@kernel.org> <20230417023911-mutt-send-email-mst@kernel.org> <20230417030713-mutt-send-email-mst@kernel.org> <20230417051816-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 17, 2023 at 10:04:56AM +0000, Alvaro Karsz wrote: > > > So, what do you think, we should fix virtio-net to work with smaller rings? we should fail probe? > > > > > > I think that since this never came up until now, there is no big demand to such small rings. > > > > The worry is that once we start failing probe there's just a tiny chance > > hosts begin to rely on us failing probe then we won't be able to fix it. > > So it depends on the size of the patch I think. So far it seems small enough > > that wasting code on failing probe isn't worth it. > > > > I see your point. > Regardless, we'll need to fail probe in some cases. > ring size of 1 for example (if I'm not mistaken) Hmm. We can make it work if we increase hard header size, then there will always be room for vnet header. > control vq even needs a bigger ring. Why does it? > Maybe we can fix virtnet to allow smaller rings + fail probe in some cases, all in the same patch/patchset. If we can't make it work then yes. -- MST