[PATCH v8 16/16] Documentation/filesystems/resctrl: Add footnote for telemetry fstab mount caveat

[Tony Luck <tony.luck@intel.com>]

Add a footnote to the 'If telemetry monitoring is enabled' sentence noting
that the PMT driver enumerates telemetry features asynchronously, so an
automatic mount of resctrl from /etc/fstab at boot may occur before those
features are available, resulting in them not being enabled.

The time for enumeration is only a few seconds, so retrying the remount
should work.

Assisted-by: Claude:Sonnet_4.6
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
v8:
	Added to footnote that a remount should fix

 Documentation/filesystems/resctrl.rst | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index b003bed339fd..942194beebc8 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -620,7 +620,7 @@ When monitoring is enabled all MON groups will also contain:
 	each instance of an L3 cache. Each directory contains files for the enabled
 	L3 events (e.g. "llc_occupancy", "mbm_total_bytes", and "mbm_local_bytes").
 
-	If telemetry monitoring is enabled, there will be a "mon_PERF_PKG_YY"
+	If telemetry monitoring is enabled [#]_, there will be a "mon_PERF_PKG_YY"
 	directory for each physical processor package. Each directory contains
 	files for the enabled telemetry events (e.g. "core_energy". "activity",
 	"uops_retired", etc.)
@@ -659,6 +659,11 @@ When monitoring is enabled all MON groups will also contain:
 	returned if the MBM event does not have an assigned counter in the
 	CTRL_MON group nor in any of its associated MON groups.
 
+.. [#] Telemetry features are enumerated asynchronously by the PMT driver. If
+   resctrl is automatically mounted from ``/etc/fstab`` at boot, the telemetry
+   features may not yet be available at mount time and will therefore not be
+   enabled. Remounting a few seconds later should fix this.
+
 "mon_hw_id":
 	Available only with debug option. The identifier used by hardware
 	for the monitor group. On x86 this is the RMID.
-- 
2.54.0