From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 11 Aug 2022 19:27:51 +0200 From: Halil Pasic Subject: Re: [virtio-dev] Re: [PATCH 1/4] content: Introduce driver/device auxiliary notifications Message-ID: <20220811192751.62897b2e.pasic@linux.ibm.com> In-Reply-To: <87ilmzcffd.fsf@redhat.com> References: <20220330152105.3770439-1-usama.arif@bytedance.com> <20220330152105.3770439-2-usama.arif@bytedance.com> <20220809160711-mutt-send-email-mst@kernel.org> <87r11octk4.fsf@redhat.com> <20220810194108.78059919.pasic@linux.ibm.com> <20220810152105-mutt-send-email-mst@kernel.org> <87ilmzcffd.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit To: Cornelia Huck Cc: "Michael S. Tsirkin" , Usama Arif , virtio-dev@lists.oasis-open.org, stefanha@redhat.com, ndragazis@arrikto.com, fam.zheng@bytedance.com, liangma@liangbit.com, Halil Pasic List-ID: On Thu, 11 Aug 2022 11:12:06 +0200 Cornelia Huck wrote: > On Wed, Aug 10 2022, "Michael S. Tsirkin" wrote: > > > On Wed, Aug 10, 2022 at 07:41:08PM +0200, Halil Pasic wrote: > >> On Wed, 10 Aug 2022 11:54:35 +0200 > >> Cornelia Huck wrote: > >> > This highlights another problem, however: When we introduce new features > >> > that require a transport-specific implementation, we often end up with a > >> > PCI implementation, but sometimes MMIO and more often ccw are left > >> > behind -- which is understandable, as PCI is what most people use, and > >> > ccw is something only a very few people are familiar with. This sadly > >> > means that we have a backlog of features supported in PCI, but not in > >> > ccw... requiring implementations for ccw would put an undue burden on > >> > contributors, as most of them are unlikely to write anything for a > >> > mainframe, ever. On the flip side, I do not have enough bandwith to deal > >> > with all of this. > >> > >> I'm completely with you in a sense that I see the same problem. I think > >> we have to get these resolved on a case by case basis. In my opinion at > >> least in theory it would make a big difference, whether the new feature > >> obligatory or not. But since VIRTIO is big on compatibility, and also > >> cares about the initial investment required, in practice, I think, we > >> are mostly good with the transports delivering features on their own > >> schedule. What I mean here is: it is kind of difficult to make a new > >> facility (like shm, or aux notifications) mandatory, because stuff > >> that conform to a previous incarnation of the spec would become > >> non-conform. > > I don't think there's a big case for making new things mandatory; > everything should be guarded by a feature bit or similar. Yes! I tried to say the same, just differently :) > > >> > >> And the people who care about the particular transport, and the users > >> of the transport (indirectly also platforms) should make up their own > >> mind with regards to whether and when to invest into the new facilities > >> and the new tech and opportunities associated with those. > > PCI will probably satisfy the needs of the vast majority of users, and > MMIO is not too alien to just change at the same time. ccw is the big > problem. Is IBM still spending resources on virtio-ccw? [My own > involvement with s390x has dwindled a lot, so it would be great to see > some of it picked up by others. Certainly not trying to pin everything > on Halil, though.] Yes! IBM is definitely (still) invested in virtio-ccw! I don't work on Virtio on s390x full time any more, but I'm totally committed to fulfilling my duties as a TC member and as the virtio-ccw sub-maintainer. IBM is looking for a solution to at least replace what the Virtio community has lost with me gaining new responsibilities not closely related to Virtio. BTW, should I not show up in time on some discussion, mentioning my name in the body of the email should help. I auto-tag my emails, and I have a separate tag for that. When I'm completely under water I check for that tag to avoid not showing up when my name is called :D Thanks for calling my name occasionally! Regards, Halil