Re: [PATCH v1] fs/resctrl: Add missing kconfig entry for CONFIG_RESCTRL_ASSIGN_FIXED

From: Babu Moger

Date: Tue Jan 13 2026 - 14:10:19 EST


Hi Ben,

On 1/13/26 08:49, Ben Horgan wrote:
The commit 3b497c3f4f04 ("fs/resctrl: Introduce the interface to display
monitoring modes") introduced CONFIG_RESCTRL_ASSIGN_FIXED but did not add
the kconfig entry. Add this.
Add this -> Add the missing configuration option  or Add the missing Kconfig option. ?

Also, take the opportunity ensure that any user attempt to change the
assign mode fails from the resctrl code rather than delegating to the arch

assign mode -> counter assignment mode


specific code and let the user know by adding a message in last_cmd_status.

Fixes: 3b497c3f4f04 ("fs/resctrl: Introduce the interface to display monitoring modes")
Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
---
fs/resctrl/Kconfig | 8 ++++++++
fs/resctrl/monitor.c | 6 ++++++
2 files changed, 14 insertions(+)

diff --git a/fs/resctrl/Kconfig b/fs/resctrl/Kconfig
index 21671301bd8a..bdf9e11502fa 100644
--- a/fs/resctrl/Kconfig
+++ b/fs/resctrl/Kconfig
@@ -37,3 +37,11 @@ config RESCTRL_RMID_DEPENDS_ON_CLOSID
Enabled by the architecture when the RMID values depend on the CLOSID.
This causes the CLOSID allocator to search for CLOSID with clean
RMID.
+
+config RESCTRL_ASSIGN_FIXED
+ bool
+ depends on RESCTRL_FS
+ help
+ Enabled by the architecture when the counter assignment mode is not
+ configurable. This ensures that counter assignment is not advertised as
+ configurable and configuration attempts fail.
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 572a9925bd6c..888e303c18a2 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -1434,6 +1434,12 @@ ssize_t resctrl_mbm_assign_mode_write(struct kernfs_open_file *of, char *buf,
rdt_last_cmd_clear();
+ if (IS_ENABLED(CONFIG_RESCTRL_ASSIGN_FIXED)) {
+ ret = -EINVAL;
+ rdt_last_cmd_puts("assign mode is not configurable\n");

assign mode -> counter assignment mode


+ goto out_unlock;
+ }
+
if (!strcmp(buf, "default")) {
enable = 0;
} else if (!strcmp(buf, "mbm_event")) {