From nobody Thu Apr 2 12:14:38 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4D7FC38228E; Sun, 29 Mar 2026 16:35:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774802131; cv=none; b=WYRduX4YqL8ZoNJ/ykk0u7dSG4jGu1oiEXjIuM5blXwy3GcDFPBb1MQ0a2zo3oqwRLWo+IyTyPNctAbsTyvO4JfFsf3XdAs4S7bYXd3CDdj5aPE6t2FHvuMdCP8KLaoZ3gzzlzs2kKJHdkp4iFInwCMr+0ybUYzBYAgeaCoRU+4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774802131; c=relaxed/simple; bh=6wzddMfUQyGGtHJTwF0gZAbRgVKVvLunzYpai4YkSBg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Y7zzU3Ywg/aYclJ+otpLE3uw9qPHck07LsE4Rv4qdBGTcQ8T+vcBL8Z32WKm14H7dMT57+/BLgMSuQ3YWN9B/XleQE97fP0puKf2toaC1UwrHaawSFwbVchv00miJZX6xhe4mg89PrI1Cwk0vdd0+NWGPF/MIa1XW5d4hy2BEUU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=pSeNA74C; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="pSeNA74C" 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 CA605451B; Sun, 29 Mar 2026 09:35:23 -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 9FAFF3F915; Sun, 29 Mar 2026 09:35:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1774802129; bh=6wzddMfUQyGGtHJTwF0gZAbRgVKVvLunzYpai4YkSBg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pSeNA74CAx7djO856jVtla60xS71CAxUgKCgH3O1AA3gBb8aLRUH8PRRntLS/wqVz jDkwRcetmJ7imYb5jLHgT+JQ/8EM8YUza9rBSVnA5b6My9oejxtTv5aGE3KQ9VnAST ge0ZnfIRC8AHAn+FcfQGL/cmqZm0GNHEo/is6ZNk= 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, dan.carpenter@linaro.org, d-gole@ti.com, jonathan.cameron@huawei.com, elif.topuz@arm.com, lukasz.luba@arm.com, philip.radford@arm.com, brauner@kernel.org, souvik.chakravarty@arm.com, Cristian Marussi , Jonathan Corbet , Shuah Khan Subject: [PATCH v3 23/24] fs/stlmfs: Document lazy mode and related mount option Date: Sun, 29 Mar 2026 17:33:34 +0100 Message-ID: <20260329163337.637393-24-cristian.marussi@arm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260329163337.637393-1-cristian.marussi@arm.com> References: <20260329163337.637393-1-cristian.marussi@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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/filesyste= ms/stlmfs.rst index a775da24f320..9a5c8bf588c8 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. =20 -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/*. =20 Since inodes represent the discovered Telemetry entities, which in turn are statically defined at the platform level and immutable throughout the same @@ -105,6 +109,19 @@ The filesystem can be typically mounted with:: =20 mount -t stlmfs none /sys/fs/arm_telemetry =20 +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. + It will proceed to create a top subdirectory for each of the discovered SCMI Telemetry instances named as 'tlm_' under which it will create the following directory structure:: --=20 2.53.0