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Mon, 19 Oct 2026 02:09:51 +0000 Received: from JohnnyFan (unknown [172.21.64.24]) by smtprelay.cixcomputing.com (Postfix) with ESMTPSA id A468942C6447; Mon, 19 Oct 2026 10:09:50 +0800 (CST) Date: Mon, 19 Oct 2026 10:09:44 +0800 From: Johnny Fan To: Leo Yan Cc: Marc Zyngier , will@kernel.org, mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, james.clark@linaro.org, jeremy.linton@arm.com, cix-kernel-upstream@cixtech.com, bob.zhang@cixtech.com, jie.fu@cixtech.com, Fugang Duan Subject: Re: [PATCH] perf: arm_spe: Support heterogeneous ACPI systems Message-ID: References: <20261015062908.3565761-1-johnny.fan@cixtech.com> <86mrsf1bnv.wl-maz@kernel.org> <20261015141926.GC26205@e132581.arm.com> <20261016100538.GE26205@e132581.arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261016100538.GE26205@e132581.arm.com> X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: OSA0EPF000000C8:EE_|TY0PR06MB5152:EE_ X-MS-Office365-Filtering-Correlation-Id: 9977b793-9b7d-4c74-32e2-08df2d860f84 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|23010399003|82310400026|36860700016|4143699003|56012099006|10067099003|22082099003|18002099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: hH6nUkKBULCYGS0X4T+TKo8i1f5HbQB4y+mSspeBAh3h1nOKziKiz5r2evkI43WCisnP9sIjI7wJrpiQvhzsLfYuFVU5MWoXqjFbLbwGOg/adWvw6JzjE6T8NOuYvCxepwO+i8y/65rOWf2yap6Qg6OO/gtX130hUS4pKcto5Gpk6zOj4zwC2Imm9ape4p65mCqEB3hWIQjgrN6X+2n1+gFI7abnodOdBr29oeQO/FdIUnksvOVa9m7lZ45QRuiAc2RL3/SnmRTeNvXPRRPG3MQm2LPdzGe1u/HNczvTocXucCe498KWve57sgI7BXwKSzz3X0fcd+zizNR6OwT38WNS+nCctSX32Q3idN5mqIt4EW7RxP2l9+9rDKX9mSJ3Ni0tVXmR80PCVDzzVLorKVHhmGNL4+rJTqidH6/Qt3AyZnIEyfn5zcloyUOKzXsc X-OriginatorOrg: cixtech.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Oct 2026 02:09:51.6647 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 9977b793-9b7d-4c74-32e2-08df2d860f84 X-MS-Exchange-CrossTenant-Id: 0409f77a-e53d-4d23-943e-ccade7cb4811 X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=0409f77a-e53d-4d23-943e-ccade7cb4811;Ip=[222.71.101.198];Helo=[smtprelay.cixcomputing.com] X-MS-Exchange-CrossTenant-AuthSource: OSA0EPF000000C8.apcprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: TY0PR06MB5152 On Fri, Oct 16, 2026 at 11:05:38AM +0100, Leo Yan wrote: > SPE driver supports heterogeneous systems. If firmware creates proper > devices based on CPU topology, the driver can probe multiple instances. > > So "registration is limited to homogeneous systems" is not quite right. You are right, I meant the ACPI registration path in arm_pmu_acpi.c. It registers a single static SPE device, and only if every possible CPU agrees on both the implementation tag (hetid) and the SPE interrupt number -- a CPU that does not implement SPE reports 0, which breaks that agreement, so a heterogeneous machine gets no SPE device at all (the boot still succeeds; SPE is just absent). As Jeremy pointed out, the fix is to group the CPUs by (hetid, GSIV) and create one device per group, like DT does with PPI partitions. The driver already handles multiple instances; how each one gets its supported_cpus is the plumbing question I asked Marc about. Thanks, Johnny