From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-1299-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id A3388985FB4 for ; Wed, 27 May 2020 06:06:28 +0000 (UTC) Date: Wed, 27 May 2020 08:06:10 +0200 From: Cornelia Huck Message-ID: <20200527080610.100af355.cohuck@redhat.com> In-Reply-To: References: <158994007522.397236.7536927155973222190.stgit@ahduyck-workstation> <158994014779.397236.836253101843237605.stgit@ahduyck-workstation> <60278259-9a04-77ab-f96f-c13bc2ffb070@redhat.com> <53e66faa-ed7f-f7c1-6284-1e2a6e63c936@redhat.com> <733c9230-1bec-11f2-9fc9-ed53beedbc66@redhat.com> <20200526173835.4a839ec6.cohuck@redhat.com> MIME-Version: 1.0 Subject: Re: [virtio-comment] [PATCH v3 2/3] content: Document balloon feature page poison Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit To: Alexander Duyck Cc: David Hildenbrand , "Michael S. Tsirkin" , virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org, "Wang, Wei W" List-ID: On Tue, 26 May 2020 20:20:21 -0700 Alexander Duyck wrote: > On Tue, May 26, 2020 at 8:38 AM Cornelia Huck wrote: > > > > On Tue, 26 May 2020 17:28:00 +0200 > > David Hildenbrand wrote: > > > > > On 26.05.20 16:50, Alexander Duyck wrote: > > > > On Tue, May 26, 2020 at 1:24 AM David Hildenbrand wrote: > > > > > >> Still wondering what to do with free page hinting ... in the meantime > > > >> I'll have a look at free page reporting :) > > > > > > > > The problem is it is already out there so I worry we wouldn't ever be > > > > able to get rid of it. At most we could deprecate it, but we are still > > > > stuck with it consuming bit resources and such. > > > > > > Yeah, that's not an issue, they will simply turn to dead bits with > > > minimal documentation. I just don't see us fixing/supporting that > > > feature, really. Let's see what @MST things when he has time to look > > > into this. > > > > > > > If free page hinting is broken enough that we don't want anybody to try > > implementing it, we maybe could: > > > > - reserve the feature bit, > > - say that the device SHOULD NOT offer it, > > - say that the driver SHOULD NOT accept it? > > > > Would avoid conflicts, and tell implementors that they should not > > bother. (We can then proceed to start deprecating the Linux/QEMU > > implementations.) > > What I might do is just try to work around it for now. I might > re-order my patches so that I can push the page poison and free page > reporting bits with the free page hinting changes at the end of the > set. That way if we decide to take a different route then we can > always go back and change that later and it won't have an impact on > the earlier changes. Maybe: - only add the hinting feature bit as reserved, - document page poison and free page reporting, - and then think about what to do with the hinting? Just to make it clear that there is another feature bit out there; but maybe that is overkill and we should just go ahead with patches 2/3 for now. This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. In order to verify user consent to the Feedback License terms and to minimize spam in the list archive, subscription is required before posting. Subscribe: virtio-comment-subscribe@lists.oasis-open.org Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org List help: virtio-comment-help@lists.oasis-open.org List archive: https://lists.oasis-open.org/archives/virtio-comment/ Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists Committee: https://www.oasis-open.org/committees/virtio/ Join OASIS: https://www.oasis-open.org/join/