linux-kernel - RE: [PATCH v6 1/3] x86/resctrl: Add mount option "mba_MBps

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Message-ID: <SJ1PR11MB6083DA80600EC76FDBCECF79FC8DA@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date:   Wed, 13 Dec 2023 01:07:13 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     "Chatre, Reinette" <reinette.chatre@...el.com>
CC:     Peter Newman <peternewman@...gle.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Shuah Khan <skhan@...uxfoundation.org>,
        "x86@...nel.org" <x86@...nel.org>,
        Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "patches@...ts.linux.dev" <patches@...ts.linux.dev>
Subject: RE: [PATCH v6 1/3] x86/resctrl: Add mount option "mba_MBps_event"

>> 	case Opt_mba_mbps:
>> 		if (!supports_mba_mbps() || ctx->enable_mba_mbps)
>> 			return -EINVAL;
>
> I am not familiar with the API but it seems that invalfc() is available
> to communicate a more useful message to user space than the default one
> shown in changelog of patch #2.

I experimented with invalfc(). It seems to be the answer to this part of the
mount error message:

       dmesg(1) may have more information after failed mount system call.

because dmesg(1) does indeed include whatever message that is provided
by the invalfc() call (including automatically adding the prefix "resctrl: ").

I'll work on incorporating your other feedback, but I'm unlikely to get it
all done and tested before the end of this week. I'll be on vacation
the last two weeks of the year. So v7 of this series will have to wait
until 2024.

Thanks

-Tony