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Tue, 6 May 2025 06:39:27 GMT Received: from smtprelay04.fra02v.mail.ibm.com ([9.218.2.228]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 46dxymj1x5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 06 May 2025 06:39:27 +0000 Received: from smtpav01.fra02v.mail.ibm.com (smtpav01.fra02v.mail.ibm.com [10.20.54.100]) by smtprelay04.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 5466dNAm13828448 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 6 May 2025 06:39:23 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A7F9F20043; Tue, 6 May 2025 06:39:23 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7A5E020040; Tue, 6 May 2025 06:39:23 +0000 (GMT) Received: from li-978a334c-2cba-11b2-a85c-a0743a31b510.ibm.com (unknown [9.155.197.178]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 6 May 2025 06:39:23 +0000 (GMT) Message-ID: Subject: Re: [PATCH v4 4/4] hw/s390x: compat handling for backward migration From: Nina Schoetterl-Glausch To: Shalini Chellathurai Saroja Cc: qemu-s390x mailing list , Thomas Huth , Daniel Berrange , qemu-devel mailing list , Hendrik Brueckner Date: Tue, 06 May 2025 08:39:23 +0200 In-Reply-To: <7390ada124fe80862e7661672c75fda4@linux.ibm.com> References: <20250410150934.1331433-1-shalini@linux.ibm.com> <20250410150934.1331433-5-shalini@linux.ibm.com> <7390ada124fe80862e7661672c75fda4@linux.ibm.com> Content-Type: text/plain; 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envelope-from=nsg@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=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, 2025-05-05 at 10:54 +0200, Shalini Chellathurai Saroja wrote: > On 2025-04-28 14:05, Nina Schoetterl-Glausch wrote: > > On Thu, 2025-04-10 at 17:09 +0200, Shalini Chellathurai Saroja wrote: > > > Add Control-Program Identification (CPI) device to QOM only when the= =20 > > > virtual > > > machine supports CPI. CPI is supported from "s390-ccw-virtio-10.0"= =20 > > > machine > > > and higher. > > >=20 > > > Signed-off-by: Shalini Chellathurai Saroja > > > --- > > > hw/s390x/s390-virtio-ccw.c | 10 +++++++++- > > > include/hw/s390x/s390-virtio-ccw.h | 1 + > > > 2 files changed, 10 insertions(+), 1 deletion(-) > > >=20 > > > diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c > > > index 7f28cbd1de..81832ee638 100644 > > > --- a/hw/s390x/s390-virtio-ccw.c > > > +++ b/hw/s390x/s390-virtio-ccw.c [...] > > Fixing this in a separate commit could be bad for bisecting. >=20 > Ok. >=20 > > You introduce use_cpi in an earlier commit set to false and > > then flipping it in the migration patch for new machines. > > This way there is no broken intermediate state. > >=20 > > I would also squash the compat migration changes into the previous > > patch. > >=20 >=20 > Hello Nina, >=20 > If use_cpi is set to false in patch 1, then the sclpcpi device will not= =20 > be instantiated even for new machines at that point. The sclpcpi device= =20 > will only be instantiated when the use_cpi is set to true in the=20 > migration patch. >=20 > I prefer to squash this entire patch to patch 1, then the sclpcpi device= =20 > will only be instantiated for new machines with the code in patch 1=20 > itself and will not be dependent on the migration patch. I like this=20 > approach as the logic to add sclpcpi device is complete in patch 1. >=20 > What do you think?, thank you. Sounds good! [...] --=20 IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Wolfgang Wendt Gesch=C3=A4ftsf=C3=BChrung: David Faller Sitz der Gesellschaft: B=C3=B6blingen / Registergericht: Amtsgericht Stuttg= art, HRB 243294