linux-kernel - Re: [PATCH v1] fs/resctrl: Add missing kconfig entry for CONFIG_RESCTRL_ASSIGN

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Message-ID: <d07db02d-4c1c-46c5-bd90-9ab579158744@amd.com>
Date: Tue, 13 Jan 2026 13:10:13 -0600
From: Babu Moger <bmoger@....com>
To: Ben Horgan <ben.horgan@....com>, linux-kernel@...r.kernel.org
Cc: tony.luck@...el.com, reinette.chatre@...el.com, Dave.Martin@....com,
 james.morse@....com, babu.moger@....com, bp@...en8.de
Subject: Re: [PATCH v1] fs/resctrl: Add missing kconfig entry for
 CONFIG_RESCTRL_ASSIGN_FIXED

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@....com>
> ---
>   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")) {