linux-kernel - [PATCH v2 16/17] fs/stlmfs: Document lazy mode and related mount option

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Message-ID: <20260114114638.2290765-17-cristian.marussi@arm.com>
Date: Wed, 14 Jan 2026 11:46:20 +0000
From: Cristian Marussi <cristian.marussi@....com>
To: linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	arm-scmi@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Cc: sudeep.holla@....com,
	james.quinlan@...adcom.com,
	f.fainelli@...il.com,
	vincent.guittot@...aro.org,
	etienne.carriere@...com,
	peng.fan@....nxp.com,
	michal.simek@....com,
	dan.carpenter@...aro.org,
	d-gole@...com,
	jonathan.cameron@...wei.com,
	elif.topuz@....com,
	lukasz.luba@....com,
	philip.radford@....com,
	souvik.chakravarty@....com,
	Cristian Marussi <cristian.marussi@....com>
Subject: [PATCH v2 16/17] fs/stlmfs: Document lazy mode and related mount option

Document optional lazy enumeration behaviour and related mount option.

Signed-off-by: Cristian Marussi <cristian.marussi@....com>
---
 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 cc9585f77ba5..79633cdc71b8 100644
--- a/Documentation/filesystems/stlmfs.rst
+++ b/Documentation/filesystems/stlmfs.rst
@@ -73,8 +73,12 @@ 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
@@ -104,6 +108,19 @@ The filesystem can be typically mounted with::
 
 	mount -t stlmfs none /sys/fs/arm_telemetry
 
+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_<N>' under which it will create
 the following directory structure::
-- 
2.52.0