Re: [PATCH] perf/core: move all of the pmu devices into their own location

Greg Kroah-Hartman
2025-02-04T17:12:10Z

On Tue, Feb 04, 2025 at 11:41:38AM -0500, Vince Weaver wrote:
> On Tue, 4 Feb 2025, Greg Kroah-Hartman wrote:
>
> >
> > It seems that the majority of the perf code IS looking in the correct
> > place, just mem-events.c seemed wrong.
>
> I hate to tell you, but other places in userspace are depending on the
> current setup. libpfm4, used by PAPI, is looking directly in /sys/devices
> for pmus and will break with the changes you are planning.

Then that too needs to be fixed, sorry. Again, devices can, and will,
move around in /sys/devices/ you can never hard-code any paths there.
Any userspace code must ALWAYS be able to handle that, that's a sysfs
requirement.

And do you have a link to the source for that code? Good news is that
if the code is fixed in userspace, it will work for any kernel (old or
new).

thanks,

greg k-h