linux-kernel - Re: [PATCH v11 04/13] x86/cpufeatures: Add Bandwidth Monitoring Event Configuration feature flag

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Date:   Tue, 24 Jan 2023 08:59:28 -0800
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     <babu.moger@....com>, Borislav Petkov <bp@...en8.de>
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Subject: Re: [PATCH v11 04/13] x86/cpufeatures: Add Bandwidth Monitoring Event
 Configuration feature flag

Hi Babu,

On 1/24/2023 8:06 AM, Moger, Babu wrote:
> 
> On 1/24/23 09:10, Borislav Petkov wrote:
>> On Tue, Jan 24, 2023 at 08:11:21AM -0600, Moger, Babu wrote:
>>> Understood. I am planning to add resctrl feature list inside
>>> /sys/fs/resctrl/info/ in my next series.
>> Maybe I wasn't as clear as I hoped for:
>>
>> so you have a couple of flags in /proc/cpuinfo which are actively being used by
>> tools.
> Those flags will be there. Not planning to remove them.
>>
>> Why would you want to move the flags somewhere else and do the extra work for no
>> apparent reason?
> 
> With this series(v12) we have added two new cpuid features(SMBA and BMEC).
> 
> But these features are not visible in /proc/cpuinfo. Planning to add them
> in /sys/fs/resctrl/info.
> 
> So, users can see them here. 

Could you please elaborate what you are planning to do? 

Existence and support for SMBA and BMEC is already visible to user space
in your current series:
* On a system that supports SMBA with the needed kernel support users will
  find the /sys/fs/resctrl/info/SMBA directory with enumerated properties
  as well as SMBA within the schemata file.
* On a system that supports BMEC with the needed kernel support users will
  find the relevant files listed within /sys/fs/resctrl/info/L3_MON/mon_features.

Reinette