Re: [PATCH v4 5/7] x86/resctrl: Resolve PMT and TPMI symbols at runtime

[Reinette Chatre]

Hi Tony,

On 4/7/26 11:13 AM, Luck, Tony wrote:
...
> Adding a "resctrl" line to /etc/fstab attempts the mount at 39.667. Three
> seconds too early. No PMT events are found, and code in this V4 version
> of the patch series marks the system as AET_NOT_PRESENT and will never
> look again :-(
> 
> I can drop the AET_NOT_PRESENT state so that a retry will succeed. I don't
> see another fix other than to document this limitation.
> 
> Workarounds are:
> 1) Change the CONFIG to build pmt_telemetry into the kernel (where we
>    are today, but haven't heard from Linux distros like Red Hat, SUSE etc.
>    on whether this is acceptable.)
> 2) Delay mounting the resctrl file system.

As I mentioned in https://lore.kernel.org/lkml/e85cd466-2202-4b40-82ed-91e421d8e073@xxxxxxxxx/
I find (2) to be a poor user interface since it (a) requires user space to
somehow know that the system supports AET and then (b) either delay for some
indeterminate time or repetitively (for some indeterminate count) remount resctrl
to obtain needed features. 

Considering all the complications, could you please provide the motivation
for this series? I should have checked for this first. The cover letter does not
contain this information.

Reinette