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 10ADFC678D5 for ; Wed, 8 Mar 2023 15:05:32 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by ws5-mx01.kavi.com (Postfix) with ESMTP id 4C0882B146 for ; Wed, 8 Mar 2023 15:05:31 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by host09.ws5.connectedcommunity.org (Postfix) with QMQP id 38D092ACE8; Wed, 8 Mar 2023 15:05:31 +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 3CBDD9866F0 for ; Wed, 8 Mar 2023 15:04:14 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: SO9kk2EqOIGs9HSgXQrMuA-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678287851; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=uOm5iLTyvYuZkGNifsVKGabJV5p81xvJ7XKXqE55NuA=; b=vizK4/uTopD9MRQSopWpZNolZXnD/9rly7UKhMSh43bMGkzQDXq5bs3BDzXazP0xRI KRSNziP6lHPde+j1z2bFBnIAn/UeCWKLMkAfm/OfZC5qzaEF0D5vnhOXAec4qOHNRwTP dgDLH7aF2DX//GS6MyqILe6Oz7VtL1Ccq6InkZhBPwmB6GZDaJZq7dVmziFTJV5WJLrn zdC4vQrIvjOflI6Jrz84WujL8Jb+qveAHa4KW3wcPQoGZA3kV/CqWRN9lz8rysoSTIFQ KB9touJyH7y7pkjG05U3//uh0VvOcw4ujgdlAKKVsXvZqftfDwUAa8zKJJPrg4SjrQAK Qcjg== X-Gm-Message-State: AO0yUKVDEm+0bNm3Cz829nQO9XsNml8VSUiBw025i6qGEUkBNCuLLNKg o4P5LV8RhzvUt05WQz7hPabMlmkWQc/nro8F0gYv134NpbJ4uwCfiAhqBuaoQOK1i0CAKxUG9ep QrNjVs287Q3o7OYQzFXPqYlmMjNn4 X-Received: by 2002:adf:e30d:0:b0:2ca:f86a:9643 with SMTP id b13-20020adfe30d000000b002caf86a9643mr12775051wrj.0.1678287850783; Wed, 08 Mar 2023 07:04:10 -0800 (PST) X-Google-Smtp-Source: AK7set8THxZbNAypBX0eNX63sSaBP4T22RG0SEQqvTx2BCqHbd7aKjiaM6PPNyeucewaAKYav+3LOg== X-Received: by 2002:adf:e30d:0:b0:2ca:f86a:9643 with SMTP id b13-20020adfe30d000000b002caf86a9643mr12775028wrj.0.1678287850452; Wed, 08 Mar 2023 07:04:10 -0800 (PST) Date: Wed, 8 Mar 2023 10:04:05 -0500 From: "Michael S. Tsirkin" To: Cornelia Huck Cc: David Edmondson , 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 Message-ID: <20230308100357-mutt-send-email-mst@kernel.org> References: <0a784140387c2a592f7e1e7bbc5ae926ec5b45da.1677761896.git.mst@redhat.com> <20230306165907-mutt-send-email-mst@kernel.org> <87fsafl452.fsf@redhat.com> MIME-Version: 1.0 In-Reply-To: <87fsafl452.fsf@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [virtio-dev] Re: [virtio] [PATCH v10 01/10] virtio: document forward compatibility guarantees On Wed, Mar 08, 2023 at 03:16:41PM +0100, Cornelia Huck wrote: > 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..." > > ? ok > 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