From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 11 Oct 2021 12:00:03 -0400 From: "Michael S. Tsirkin" Subject: Re: [PATCH v2] Add device reset timeout field Message-ID: <20211011115716-mutt-send-email-mst@kernel.org> References: <20211008071903-mutt-send-email-mst@kernel.org> <87lf33ybz7.fsf@redhat.com> <20211008085134-mutt-send-email-mst@kernel.org> <20211008185926-mutt-send-email-mst@kernel.org> <871r4ry5do.fsf@redhat.com> MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Disposition: inline To: Parav Pandit Cc: Cornelia Huck , "virtio-dev@lists.oasis-open.org" , Max Gurtovoy , Shahaf Shuler , Oren Duer List-ID: On Mon, Oct 11, 2021 at 03:44:14PM +0000, Parav Pandit wrote: > > > This is unlikely to work the reset is completed. Because a real device > > implementing this would prefer to do this in fw for 1000 virtio devices sitting on > > the physical card. > > > And it is very much driven by such implementation at device devel. > > > So it cannot update the counter value if reset is not completed for the device. > > > > > > I think read only device reset timeout is most elegant option during device > > initialization phase that eliminates infinite loop of today. > > > > Why can't a driver just go ahead and do a timeout regardless? > o.k. lets consider this thought exercise. What is the timeout value that driver will choose if device doesn't specify one? > I explained in previous thread and you acked that actual fw based device may take longer to initialize than pure sw implementation backend. > In second example a pre-boot device can take even longer initialization time. > Sriov VF device may initialize lot faster. > Instead of driver having such transport, and device specific checks, (or some very short or very long timeout), we propose, that let device mention such timeout value. Parav I think you are conflating reset with initialization time. initialization is just for host boot which takes seconds anyway - but no, minutes is not reasonable their, either. reset affects guest boot. This needs to complete in milliseconds. This conflation is IMHO one of the problems with this proposal. -- MST