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Mon, 21 Sep 2026 14:37:23 -0700 (PDT) X-Received: by 2002:a17:902:ebc6:b0:2dd:c053:9c6e with SMTP id d9443c01a7336-2ddc0539da7mr117471595ad.36.1790026642576; Mon, 21 Sep 2026 14:37:22 -0700 (PDT) Received: from localhost ([50.35.44.179]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-33e5ec0d55esm650212eec.20.2026.09.21.14.37.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Sep 2026 14:37:22 -0700 (PDT) Date: Mon, 21 Sep 2026 14:37:18 -0700 From: Jonathan Cameron To: Suzuki K Poulose Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev, maz@kernel.org, will@kernel.org, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, steven.price@arm.com, aneesh.kumar@kernel.org, oupton@kernel.org, gshan@redhat.com, joey.gouly@arm.com, tabba@google.com, yuzenghui@huawei.com, linux-coco@lists.linux.dev, gankulkarni@os.amperecomputing.com, sdonthineni@nvidia.com, alpergun@google.com, fj0570is@fujitsu.com, WeiLin.Chang@arm.com, lpieralisi@kernel.org, enju.kohei@fujitsu.com Subject: Re: [PATCH v18 2/7] firmware: arm_rmm: Check for RMI support at init Message-ID: <20260921143718.00001e55@oss.qualcomm.com> In-Reply-To: References: <20260912083611.2513845-1-suzuki.poulose@arm.com> <20260912083611.2513845-3-suzuki.poulose@arm.com> <178978126541.2352296.3637463397103730192.b4-review@b4> Organization: Qualcomm X-Mailer: Claws Mail 4.4.0 (GTK 3.24.51; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Proofpoint-GUID: I8rrBby-9VUbMvi1-iRyTauW7WJSGXrp X-Authority-Analysis: v=2.4 cv=dPczC+Zb c=1 sm=1 tr=0 ts=6ab1a394 cx=c_pps a=IZJwPbhc+fLeJZngyXXI0A==:117 a=aNnz9XPx1a4JIXSYt2cE/A==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=gowsoOTTUOVcmtlkKump:22 a=7CQSdrXTAAAA:8 a=dENJxcbTWoohif9XLWkA:9 a=CjuIK1q_8ugA:10 a=uG9DUKGECoFWVXl0Dc02:22 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIxMDMxNSBTYWx0ZWRfX4DatApPGYb3a lTFitCkNoeA4SQod+nyt8XMlVCOMC3QK1bcBmmBUrsQOTJ1MalBrTzLOkiehwvwbXy3Ae9qXPmo ipYpVmXff78H2SMy60zCctNvobWQlTD4ry5MYwf8sxa3YazyRRi3iA3c4M/gbBbtQ8cwad7jkSx C1wPgH1sLGWf2rvJ3pBKI0OiBQeBZTPUOVV5b0TIsW1vFXd0ooALyFlw7Cbv+AuatyaEtPotZgb Ee3I3e0RxTXZIuekpd5t11tngmjIPZvaWujKFAg5LrWRpYXZgBw8JPP6EdlwGipQdu3yXChJaZD bzPcZwvfOpYqlBnqL3W4fOWIKPEMkRfJZWRFmI+RYIhgOvnNwQAtMPCry1dwtuTJ3bEB0/POY3B QQoSu8sdYX5/6vrp7ITxhJdIov+DtrZsvvHOWedLSzFrY1nYvXiEWzoP26phGIN6B7XBw170+dt 42ftMYsVq3jKfxIGP4g== X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIxMDMxNSBTYWx0ZWRfX3pFDXFZ3Wdlv r9KsZFyoMp55FYvBmK+py6djqgj2kRkWV8O8ndSPODYZ3oRIwGZJBaL677NjXVAWJe/aaL69B9b EJaLo5N6uyGP68Mf4w5vB2OV49Th+Xs= X-Proofpoint-ORIG-GUID: I8rrBby-9VUbMvi1-iRyTauW7WJSGXrp X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-21_06,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 malwarescore=0 phishscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 clxscore=1015 adultscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609210315 On Mon, 21 Sep 2026 10:00:20 +0100 Suzuki K Poulose wrote: > On 19/09/2026 02:27, Jonathan Cameron wrote: > >> Query the RMI version number and check if it is a compatible version. > >> The first two feature registers are read and exposed for future code to > >> use. > >> > >> We only support this for Little Endian kernels, the Big Endian kernel > >> support is anyway marked BROKEN and is being removed. > > > > Can we have a small comment here on why the default is y > > > > It's a big thing to opt into by default. Feels like defconfig > > material maybe but not in the Kconfig defaults unless I'm missing > > something. > > We need this for KVM arm64. I could drop the default here and > KVM selects this anyways. But, how far do we go on this ? > Do we need to be able to disable this completely even for KVM ? Not sure. Question for the KVM folk to decide. Lot of pre CCA systems out there and domains in which CCA may not be useful, so definitely makes sense that people will build kernels without it. I think dropping this default though makes sense if KVM can select it. Jonathan > > As such it is a relatively smaller blob: > > $ size drivers/firmware/arm_rmm/rmi.o > text data bss dec hex filename > 7477 572 1 8050 1f72 drivers/firmware/arm_rmm/rmi.o > > Cheers > Suzuki >