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Mon, 1 Dec 2025 15:10:25 +0000 (UTC) Received: from localhost (dhcp-192-223.str.redhat.com [10.33.192.223]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0212419560A7; Mon, 1 Dec 2025 15:10:23 +0000 (UTC) From: Cornelia Huck To: David Woodhouse , "Chalios, Babis" , "mst@redhat.com" , "imammedo@redhat.com" , "pbonzini@redhat.com" Cc: "qemu-devel@nongnu.org" , "Graf (AWS), Alexander" , "mzxreary@0pointer.de" Subject: Re: [RFC PATCH 2/4] hw/acpi: add new fields in VMClock ABI In-Reply-To: <8e8ab56ce4f8f2a0f0c084bd4e48958a441b40f1.camel@infradead.org> Organization: "Red Hat GmbH, Sitz: Werner-von-Siemens-Ring 12, D-85630 Grasbrunn, Handelsregister: Amtsgericht =?utf-8?Q?M=C3=BCnchen=2C?= HRB 153243, =?utf-8?Q?Gesch=C3=A4ftsf=C3=BChrer=3A?= Ryan Barnhart, Charles Cachera, Avril Crosse O'Flaherty" References: <20251201125023.18344-1-bchalios@amazon.es> <20251201125023.18344-4-bchalios@amazon.es> <87qztenykd.fsf@redhat.com> <196b8afa77ec3253006dcde712b07f4e9c70de30.camel@infradead.org> <87ldjmnwyt.fsf@redhat.com> <8e8ab56ce4f8f2a0f0c084bd4e48958a441b40f1.camel@infradead.org> User-Agent: Notmuch/0.38.3 (https://notmuchmail.org) Date: Mon, 01 Dec 2025 16:10:21 +0100 Message-ID: <87ikeqnspu.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.129.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Dec 01 2025, David Woodhouse wrote: > On Mon, 2025-12-01 at 14:38 +0100, Cornelia Huck wrote: >> On Mon, Dec 01 2025, David Woodhouse wrote: >>=20 >> > On Mon, 2025-12-01 at 14:04 +0100, Cornelia Huck wrote: >> > > On Mon, Dec 01 2025, "Chalios, Babis" wrote: >> > >=20 >> > > > VMClock now supports a vm_generation_counter field in the struct it >> > > > exposes to userspace. The field signals a disruption that happened= due >> > > > to a guest loaded from a snapshot. >> > > >=20 >> > > > Moreover, VMClock now optionally supports device notifications whe= n the >> > > > seq_count changes to a new even value. >> > > >=20 >> > > > Signed-off-by: Babis Chalios >> > > > --- >> > > > =C2=A0include/standard-headers/linux/vmclock-abi.h | 20 ++++++++++= ++++++++++ >> > > > =C2=A01 file changed, 20 insertions(+) >> > >=20 >> > > Please either do a full linux-headers update against a specific Linux >> > > kernel version, or mark this as a placeholder patch if the code is n= ot >> > > yet merged. >> >=20 >> > The Linux patches are being posted simultaneously, so they'll be in >> > Linux 6.20 (7.0?) at the earliest. We'll want to ingest the update >> > before then. >> >=20 >> > The intent is not for the Linux source to be the canonical definition >> > of the data structure; we *are* working on publishing the spec, and >> > Babis referenced the current draft. It isn't in the form of C source >> > code though, so I suspect it makes sense to keep including the Linux >> > header? >>=20 >> Oh, including the Linux header sounds fine; but as long as the code has >> not yet been merged there, this needs to be marked as not yet ready to >> merge on the QEMU side. (And it needs to be updated by a full headers >> update when merged.) > > That's exactly what we *don't* want, and why we say that the canonical > definition of this structure is the actual specification. There's no > need for QEMU to only ever follow Linux. > > In that case, probably best *not* to use the Linux header and instead > to build our own specifically for QEMU based on the specification. It > can be almost byte-for-byte identical, but just needs to live elsewhere > rather than in Yes, if you want to disentangle this, the header needs to go somewhere else in QEMU. This is only my "someone changed something in standard-headers without a headers sync" triggering ;)