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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: <20230417075645-mutt-send-email-mst@kernel.org> References: <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> <20230417073830-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: netdev@vger.kernel.org On Mon, Apr 17, 2023 at 11:51:22AM +0000, Alvaro Karsz wrote: > > > 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? > > At the moment, most of the commands chain 3 descriptors: > 1 - class + command > 2 - command specific > 3 - ack > > We could merge 1 and 2 into a single one, both are read only for the device, so I take it back, it won't need a bigger ring. > But it will need 2 descriptors at least(1 read only for the device and 1 write only for the device), so we still need to fail probe sometimes. > Yes that makes sense, it's architetural. We can disable ctrl vq though. -- MST