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[192.35.156.11]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2b6b351e38bsm747551eec.14.2026.01.15.15.51.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 15 Jan 2026 15:51:34 -0800 (PST) Message-ID: Date: Thu, 15 Jan 2026 15:51:33 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] firmware: smccc: default ARM_SMCCC_SOC_ID to disabled To: Dmitry Baryshkov Cc: Sudeep Holla , Mark Rutland , Lorenzo Pieralisi , linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, trilok.soni@oss.qualcomm.com References: <20260112-disable_smccc_soc_id-v1-1-a5bee24befb4@oss.qualcomm.com> <86331062-301b-40b1-9df1-78f7751508b4@oss.qualcomm.com> <4fab824f-8067-49d7-8e6c-dedd67a8454d@oss.qualcomm.com> Content-Language: en-US From: Satya Durga Srinivasu Prabhala In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Authority-Analysis: v=2.4 cv=JNg2csKb c=1 sm=1 tr=0 ts=69697d88 cx=c_pps a=Uww141gWH0fZj/3QKPojxA==:117 a=ZdW6uxA9NKXbfdqeeS2OGA==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Oh2cFVv5AAAA:8 a=ZFde01yRvqAbkRv1oOAA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=PxkB5W3o20Ba91AHUih5:22 a=7KeoIwV6GZqOttXkcoxL:22 X-Proofpoint-ORIG-GUID: qAlrB-dsQ5aASRHK94MuVAA-d6snao9F X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTE1MDE4OSBTYWx0ZWRfX1IK+i0c3ir31 OPk5UdJykk9+773rHE9H/P3r++3S9xP53i6lXo8b7EQn5sja05G/IADmGVA402LURO9BB5ScSj2 CVyqqND05w0hqy0YJ2aI7oYxIMHTTkp41xAhMNfAWVIJf91RU3G7GiEvMydmz8IZmQ6p5E5nB7R aXjlhGq6xS1a+nLkJ7ELOh1UwPUUc80Tmho4+b5KV+SSW0AQn8W/U16wYS/qLy/vOxo9rRCmO1S Lbsp/fj5RBARJj8hJ8w9/eNOJInbEvdF7DFgsNYfo9atY6+O5TRKyQAeWr2bhiJNbRmpbLMTPlZ xwfYnLYhwvc+5wBWsAvujvLJiIdWpJL9Jqq5jAh+PAIcxrc2DFOiS2quIMloFboP4bVIeIGqa9I +jNFY7nMGFpjfsTEhTOly1L6w/2m24XELW5AFbQcA4WLSuYZ+hQdYAjMooguJXesH7/CPuW4Zy2 GbsGY1Ex/Hkh8eiB0hQ== X-Proofpoint-GUID: qAlrB-dsQ5aASRHK94MuVAA-d6snao9F X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-15_07,2026-01-15_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 adultscore=0 suspectscore=0 priorityscore=1501 bulkscore=0 lowpriorityscore=0 clxscore=1015 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2512120000 definitions=main-2601150189 Hello Dmitry, On 1/15/2026 12:18 PM, Dmitry Baryshkov wrote: > On Thu, Jan 15, 2026 at 10:42:51AM -0800, Satya Durga Srinivasu Prabhala wrote: >> Hello Sudeep, >> >> Thanks for the feedback. >> >> On 1/14/2026 1:01 PM, Sudeep Holla wrote: >>> On Wed, Jan 14, 2026 at 08:50:23AM -0800, Satya Durga Srinivasu Prabhala wrote: >>>> Hello Sudeep, >>>> >>>> On 1/13/2026 4:29 AM, Sudeep Holla wrote: >>>>> On Mon, Jan 12, 2026 at 10:24:06PM -0800, Satya Durga Srinivasu Prabhala wrote: >>>>>> The ARM SMCCC SoC ID driver is currently enabled by default and publishes >>>>>> SMCCC-provided SoC identification into /sys/bus/soc/devices/socX/*. >>>>>> >>>>>> On platforms where a vendor SoC driver already exposes widely-consumed >>>>>> attributes (e.g. Qualcomm socinfo [1]), enabling the SMCCC driver changes >>>>>> the format of /sys/devices/soc0/soc_id (e.g. "jep106:XXYY:ZZZZ" instead >>>>>> of a vendor logical ID like "519") and breaks existing userspace consumers. >>>>>> >>>>> Instead of relying on a vendor-specific SoC driver, we should consider >>>>> disabling it and using the OS-agnostic SoC information interface provided by >>>>> the firmware. >>>> Would like to add some history here. Vendor interface existed [1] even >>>> before >>>> SMCCC SMC ID was introduced [2]. And there are several user space entities >>>> which >>>> uses the soc0 interface already. >>> True, but that's not the main point. >> That is one of the point which needs to be considered in my honest opinion. >> Vendor driver existed from long time (v3.10 Kernels) in Android >> https://android.googlesource.com/kernel/msm/+/refs/heads/android-msm-angler-3.10-marshmallow-dr/drivers/soc/qcom/socinfo.c >> and lot of user space entities in Android depends on soc0 which is not just >> limited >> Qualcomm user space, but also, 3rd party ones. >> >>>>> The presence of this interface strongly suggests that the >>>>> firmware is designed to support multiple operating systems or software stacks >>>>> that already depend on it. >>>> That is correct. We started seeing the issue with user space when our >>>> firmware >>>> started implementing support for SMCCC SOC ID recently for non-Linux based >>>> product. >>>> As the firmware remain same across OSes, user space is broken on Linux. >>> What exactly do you mean by "firmware started implementing support for SMCCC >>> SOC ID recently for non-Linux based product" ? Does that really mean that >>> you can change the firmware for Linux based products ? I don't think so and >>> hence we are in this discussion. >>> >>> 1. Either it exists in which case deal with it by disabling vendor driver >>> and/or fixing the userspace. >>> >>> or >>> >>> 2. It doesn't exist which is not a problem. >> Allow me to add some more details, so far, our firmware hasn't been >> supporting >> SMCCC SMC ID.  Due a requirement on non-Linux based product, firmware >> started >> to support the feature and same firmware is used even on Linux Android >> (android16-6.12) >> based product. >> >> I would say, firmware started supporting the feature on our newer product >> instead >> of firmware being updated on any older products. > These are two different cases. But as you explicitly state that it is > only for a new products, then you can fix the userspace to check all > SoC devices. Broken userspace was never _shipped_ on those. Though it's a new product with updated firmware which supports the SMCCC SOC ID, Kernel & user space remain same (Android16 based) and shared with other SoCs. >> Now, as the user space remain same and is relying on soc0 interface already, > Why does it have to be the same for new devices? It's a software stack composition where Kernel & User space is shared and expected to have no changes (shared with other SoCs / Products as well). >> user space is broken as SMCCC SOC ID enabled by default which gets compiled >> into Kernel and takes precedence over vendor driver which is a vendor module >> in case of Android. >> >>> The userspace >>> tool seem to have made a wrong assumption and can't expect the kernel to >>> magically fix the issue here. >>> >>> E.g. We didn't disable HMP(a.k.a big little platforms) as the assumptions >>> made by several userspace tools(e.g. lscpu IIRC) was wrong at the time. >> Sorry, at risk of repeating the same thing again, the user space was using >> soc0 interface on Linux Android products for a long time base on vendor >> implementation. While I agree that, user space had some assumptions based >> on vendor implementation, if not disabling the SMCCC SOC ID by default, we >> should at-least have a way to disable it (via cmdline) based on vendor >> requirements. > How will that command line parameter be set and passed to the kernel? Either from Device Tree or Bootloader. > > A better approach would be to fix the issue where is is broken: > - Add a switch to the firmware, letting it ignore SMCCC SOC_ID calls > (like it was beforehand) > > OR > > - Fix the userspace > > The kernel was never broken, it is not a kernel change that introduced > the regression. Why are you trying to change the kernel? If it ain't > broken, don't fix it. Sure, if we can't do anything in Kernel, we will explore these options.