From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from ws5-mx01.kavi.com (ws5-mx01.kavi.com [34.193.7.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 52824C678D5 for ; Wed, 8 Mar 2023 14:16:53 +0000 (UTC) Received: from lists.oasis-open.org (oasis.ws5.connectedcommunity.org [10.110.1.242]) by ws5-mx01.kavi.com (Postfix) with ESMTP id B428B335C1 for ; Wed, 8 Mar 2023 14:16:50 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id A2A539866FB for ; Wed, 8 Mar 2023 14:16:50 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by lists.oasis-open.org (Postfix) with QMQP id 994A29866EF; Wed, 8 Mar 2023 14:16:50 +0000 (UTC) Mailing-List: contact virtio-comment-help@lists.oasis-open.org; run by ezmlm List-ID: Sender: Precedence: bulk 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 884019866F0 for ; Wed, 8 Mar 2023 14:16:50 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: z_VWU1RYM0WiRa1VG_0svg-1 From: Cornelia Huck To: David Edmondson , "Michael S. Tsirkin" Cc: virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org, jasowang@redhat.com, sgarzare@redhat.com, stefanha@redhat.com, nrupal.jani@intel.com, Piotr.Uminski@intel.com, hang.yuan@intel.com, virtio@lists.oasis-open.org, Zhu Lingshan , pasic@linux.ibm.com, Shahaf Shuler , Parav Pandit , Max Gurtovoy In-Reply-To: Organization: Red Hat GmbH References: <0a784140387c2a592f7e1e7bbc5ae926ec5b45da.1677761896.git.mst@redhat.com> <20230306165907-mutt-send-email-mst@kernel.org> User-Agent: Notmuch/0.37 (https://notmuchmail.org) Date: Wed, 08 Mar 2023 15:16:41 +0100 Message-ID: <87fsafl452.fsf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Subject: [virtio-comment] Re: [virtio] [PATCH v10 01/10] virtio: document forward compatibility guarantees On Tue, Mar 07 2023, David Edmondson wrote: > "Michael S. Tsirkin" writes: > >> On Mon, Mar 06, 2023 at 01:53:50PM +0000, David Edmondson wrote: >>> "Michael S. Tsirkin" writes: >>> >>> > Feature negotiation forms the basis of forward compatibility >>> > guarantees of virtio but has never been properly documented. >>> > Do it now. >>> > >>> > Suggested-by: Halil Pasic >>> > Signed-off-by: Michael S. Tsirkin >>> > --- >>> > content.tex | 42 ++++++++++++++++++++++++++++++++++++++++++ >>> > 1 file changed, 42 insertions(+) >>> > >>> > diff --git a/content.tex b/content.tex >>> > index 0e474dd..0c2d917 100644 >>> > --- a/content.tex >>> > +++ b/content.tex >>> > @@ -114,21 +114,63 @@ \section{Feature Bits}\label{sec:Basic Facilities of a Virtio Device / Feature B >>> > In particular, new fields in the device configuration space are >>> > indicated by offering a new feature bit. >>> > >>> > +To keep the feature negotiation mechanism extensible, it is important >>> > +that devices \em{do not} offer any feature bits that they would not be >>> > +able to handle if the driver accepted them (even though drivers are not >>> > +supposed to accept them in the first place even if offered, according to >>> > +this version of the specification.) >>> >>> I find this (the bit in parenthesis) confusing. >>> >>> Why are drivers not supposed to accept features that they have been >>> offered, given that they can't know that the device cannot handle the >>> feature that it just offered? >>> >>> Is this alluding to the later section: >>> >>> > feature bits not described in this specification, reserved feature >>> > bits and feature bits reserved or not supported for the specific >>> > transport or the specific device type >>> >>> ? >> >> exactly. how would you put this better? given an example? > > Perhaps it would be enough to say: > >> (even though drivers are not supposed to accept unrecognised features in >> the first place even if offered, according to the specification) > > "Unrecognised" is intended as a shorthand for the whole "not described, > reserved, ...". Maybe "unrecognised or reserved"? Hm, what about "even though drivers are not supposed to accept any unspecified, reserved, or unsupported features even if offered..." ? I'm not sure how we can make this both short and descriptive enough... 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/ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from ws5-mx01.kavi.com (ws5-mx01.kavi.com [34.193.7.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 109D1C678D5 for ; Wed, 8 Mar 2023 14:16:49 +0000 (UTC) Received: from lists.oasis-open.org (oasis.ws5.connectedcommunity.org [10.110.1.242]) by ws5-mx01.kavi.com (Postfix) with ESMTP id 4CF452ACB1 for ; Wed, 8 Mar 2023 14:16:48 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 44C719866FD for ; Wed, 8 Mar 2023 14:16:48 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by lists.oasis-open.org (Postfix) with QMQP id 35A5F9866EE; Wed, 8 Mar 2023 14:16:48 +0000 (UTC) Mailing-List: contact virtio-dev-help@lists.oasis-open.org; run by ezmlm List-ID: Sender: Precedence: bulk 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 2498D9866EF for ; Wed, 8 Mar 2023 14:16:48 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: z_VWU1RYM0WiRa1VG_0svg-1 From: Cornelia Huck To: David Edmondson , "Michael S. Tsirkin" Cc: virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org, jasowang@redhat.com, sgarzare@redhat.com, stefanha@redhat.com, nrupal.jani@intel.com, Piotr.Uminski@intel.com, hang.yuan@intel.com, virtio@lists.oasis-open.org, Zhu Lingshan , pasic@linux.ibm.com, Shahaf Shuler , Parav Pandit , Max Gurtovoy In-Reply-To: Organization: Red Hat GmbH References: <0a784140387c2a592f7e1e7bbc5ae926ec5b45da.1677761896.git.mst@redhat.com> <20230306165907-mutt-send-email-mst@kernel.org> User-Agent: Notmuch/0.37 (https://notmuchmail.org) Date: Wed, 08 Mar 2023 15:16:41 +0100 Message-ID: <87fsafl452.fsf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Subject: [virtio-dev] Re: [virtio] [PATCH v10 01/10] virtio: document forward compatibility guarantees On Tue, Mar 07 2023, David Edmondson wrote: > "Michael S. Tsirkin" writes: > >> On Mon, Mar 06, 2023 at 01:53:50PM +0000, David Edmondson wrote: >>> "Michael S. Tsirkin" writes: >>> >>> > Feature negotiation forms the basis of forward compatibility >>> > guarantees of virtio but has never been properly documented. >>> > Do it now. >>> > >>> > Suggested-by: Halil Pasic >>> > Signed-off-by: Michael S. Tsirkin >>> > --- >>> > content.tex | 42 ++++++++++++++++++++++++++++++++++++++++++ >>> > 1 file changed, 42 insertions(+) >>> > >>> > diff --git a/content.tex b/content.tex >>> > index 0e474dd..0c2d917 100644 >>> > --- a/content.tex >>> > +++ b/content.tex >>> > @@ -114,21 +114,63 @@ \section{Feature Bits}\label{sec:Basic Facilities of a Virtio Device / Feature B >>> > In particular, new fields in the device configuration space are >>> > indicated by offering a new feature bit. >>> > >>> > +To keep the feature negotiation mechanism extensible, it is important >>> > +that devices \em{do not} offer any feature bits that they would not be >>> > +able to handle if the driver accepted them (even though drivers are not >>> > +supposed to accept them in the first place even if offered, according to >>> > +this version of the specification.) >>> >>> I find this (the bit in parenthesis) confusing. >>> >>> Why are drivers not supposed to accept features that they have been >>> offered, given that they can't know that the device cannot handle the >>> feature that it just offered? >>> >>> Is this alluding to the later section: >>> >>> > feature bits not described in this specification, reserved feature >>> > bits and feature bits reserved or not supported for the specific >>> > transport or the specific device type >>> >>> ? >> >> exactly. how would you put this better? given an example? > > Perhaps it would be enough to say: > >> (even though drivers are not supposed to accept unrecognised features in >> the first place even if offered, according to the specification) > > "Unrecognised" is intended as a shorthand for the whole "not described, > reserved, ...". Maybe "unrecognised or reserved"? Hm, what about "even though drivers are not supposed to accept any unspecified, reserved, or unsupported features even if offered..." ? I'm not sure how we can make this both short and descriptive enough... --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org