Hi Jason, On Tue, Mar 9, 2021 at 5:00 PM Bin Meng <bmeng...@gmail.com> wrote: > > Hi Jason, > > On Tue, Mar 9, 2021 at 4:57 PM Jason Wang <jasow...@redhat.com> wrote: > > > > > > On 2021/3/9 4:35 下午, Bin Meng wrote: > > > Hi Jason, > > > > > > On Tue, Mar 9, 2021 at 4:23 PM Jason Wang <jasow...@redhat.com> wrote: > > >> > > >> On 2021/3/8 6:22 下午, Peter Maydell wrote: > > >>> On Mon, 8 Mar 2021 at 03:48, Jason Wang <jasow...@redhat.com> wrote: > > >>>> Do we need to care about other type of networking backends? E.g socket. > > >>>> > > >>>> Or at least we should keep the padding logic if we can't audit all of > > >>>> the backends. > > >>> I think the key thing we need to do here is make a decision > > >>> and be clear about what we're doing. There are three options > > >>> I can see: > > >>> > > >>> (1) we say that the net API demands that backends pad > > >>> packets they emit to the minimum ethernet frame length > > >>> unless they specifically are intending to emit a short frame, > > >>> and we fix any backends that don't comply (or equivalently, > > >>> add support in the core code for a backend to mark itself > > >>> as "I don't pad; please do it for me"). > > >>> > > >>> (2) we say that the networking subsystem doesn't support > > >>> short packets, and just have the common code always enforce > > >>> padding short frames to the minimum length somewhere between > > >>> when it receives a packet from a backend and passes it to > > >>> a NIC model. > > >>> > > >>> (3) we say that it's the job of the NIC models to pad > > >>> short frames as they see them coming in. > > >>> > > >>> I think (3) is pretty clearly the worst of these, since it > > >>> requires every NIC model to handle it; it has no advantages > > >>> over (2) that I can see. I don't have a strong take on whether > > >>> we'd rather have (1) or (2): it's a tradeoff between whether > > >>> we support modelling of short frames vs simplicity of code. > > >>> I'd just like us to be clear about what point or points in > > >>> the code have the responsibility for padding short frames. > > >> > > >> I'm not sure how much value we can gain from (1). So (2) looks better to > > >> me. > > >> > > >> Bin or Philippe, want to send a new version? > > >> > > > I think this series does what (2) asks for. Or am I missing anything? > > > > > > It only did the padding for user/TAP. >
(hit send too soon ...) Ah, so we want this: if (sender->info->type != NET_CLIENT_DRIVER_NIC) correct? Regards, Bin