From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 92288CD98CF for ; Fri, 12 Jun 2026 22:41:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=0vqSAaryZQvtPSwaRvUVVomgPbXNrzWvP2fZpwfzj9k=; b=2vj9/h5l6UUCvVU9sHC1eawVAj SR+ZTi95Jfc+u/NvJNbMBve+gz5juUQYmp1fKkmarIU3DGrFJ+S+byjNW7AlqNaKPdG3QmRryxmdt IomSugb3aYZYS6bqkNukQ1EEWZrfidH1MiIUrdNUlFAu0WFghzTAcZ3N+Ne9QkUzkkxGFwsMe29qr 7uTEJRzCZbp8V6cvNv7etI0O01dpw2W61ZSOXQEHGfteCP+IlYQfmjEsQVAGAxYlwqIO3knQi8LG2 wgzJA2aM8ngE3NJjaOeiNiSu6JFM0jJ3d2ENVEZcWYDktLXqcVWD97zoNcKdYawLNWlcZlJrQOk1Y lETKRGuw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wYAYe-0000000Bi2b-0xrB; Fri, 12 Jun 2026 22:41:00 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wYAYN-0000000Bhjv-1fAn for linux-arm-kernel@lists.infradead.org; Fri, 12 Jun 2026 22:40:59 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E707049FF; Fri, 12 Jun 2026 15:40:37 -0700 (PDT) Received: from pluto.fritz.box (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 89A993FB7F; Fri, 12 Jun 2026 15:40:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1781304042; bh=rYNWoT8FgHcrkaH/pzU7XRjAp+88/ymTw1A/6aJvCgc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IlSb6Qi3U8df8DpFzhjdlpV4dfBvQ7A5sFn5af0QwPfcOND3YFNyqwgsQofD5VlhU +72gUw0PL+Rm+OzXwnicYGZ0+T13jqeFnNaIfUYBHRhbYYc1fbr+yMFycJR2Fny8RW E8M3XA+R2onW7E9o4S5kVecMMcNWPMe2CRkrAJac= From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, arm-scmi@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org Cc: sudeep.holla@kernel.org, james.quinlan@broadcom.com, f.fainelli@gmail.com, vincent.guittot@linaro.org, etienne.carriere@st.com, peng.fan@oss.nxp.com, michal.simek@amd.com, d-gole@ti.com, jic23@kernel.org, elif.topuz@arm.com, lukasz.luba@arm.com, philip.radford@arm.com, brauner@kernel.org, souvik.chakravarty@arm.com, leitao@kernel.org, kas@kernel.org, puranjay@kernel.org, usama.arif@linux.dev, kernel-team@meta.com, Cristian Marussi , Jonathan Corbet , Shuah Khan Subject: [PATCH v4 30/31] fs/stlmfs: Document lazy mode and related mount option Date: Fri, 12 Jun 2026 23:38:00 +0100 Message-ID: <20260612223802.1337232-31-cristian.marussi@arm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260612223802.1337232-1-cristian.marussi@arm.com> References: <20260612223802.1337232-1-cristian.marussi@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260612_154043_551751_3823C788 X-CRM114-Status: GOOD ( 11.16 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Document optional lazy enumeration behaviour and related mount option. Cc: Jonathan Corbet Cc: Shuah Khan Cc: linux-doc@vger.kernel.org Signed-off-by: Cristian Marussi --- Documentation/filesystems/stlmfs.rst | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/Documentation/filesystems/stlmfs.rst b/Documentation/filesystems/stlmfs.rst index b5b3cd649775..fe69d40f9249 100644 --- a/Documentation/filesystems/stlmfs.rst +++ b/Documentation/filesystems/stlmfs.rst @@ -74,8 +74,12 @@ Design STLMFS is a pseudo filesystem used to expose ARM SCMI Telemetry data discovered dynamically at run-time via SCMI. -Inodes are all dynamically created at mount-time from a dedicated -kmem_cache based on the gathered available SCMI Telemetry information. +Normally all of the top level file/inodes are dynamically created at +mount-time from a dedicated kmem_cache based on the gathered available +SCMI Telemetry information, but it is possible to enable a lazy enumeration +and FS population mode that delays SCMI Telemetry resources enumerations +and related FS population till the moment a user steps into the related FS +subdirectories: *des/* *groups/* and *components/*. Since inodes represent the discovered Telemetry entities, which in turn are statically defined at the platform level and immutable throughout the same @@ -128,6 +132,19 @@ Note that all of the above options are explicitly designed NOT to support a remount operation, so as not have surprising effects on permissions of already discovered/created telemetry files. +It is possible to mount it in lazy-mode by using the *lazy* mount option:: + + mount -t stlmfs -o lazy none /sys/fs/arm_telemetry + +In this latter case, the des/ groups/ and components/ directory will be +created empty at mount-time and only filled later when 'walked in'. + +This allows a user to benefit from a lazy enumeration scheme of the SCMI +Telemetry resources by delaying such, usually expensive, message exchanges +to the last possible moment: ideally, even never, if using some of the +other alternative binary interfaces that does not need any resource +enumeration at all. + Usage ===== -- 2.54.0