hwpmc: Query hwpmc for caps

[mashtizadeh]

This change allows for fine-grained capabilities per counter index. This is particularly useful for AMD where subclasses are not exposed to the general PMC code, but other architectures also have assymetric behaviors when it comes to specific counter indicies.

Sponsored by: Netflix

[github-actions]

Thank you for taking the time to contribute to FreeBSD!

There is an issue that needs to be resolved:

• Missing Signed-off-by lines (960ac84)

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Please review CONTRIBUTING.md, then update and push your branch again.

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@concussious wants to review changes to share/man/

[mashtizadeh]

@bsdimp

[mashtizadeh]

Yea this is ready unless you have any comments.

[mhorne]

This is sensible, and probably what was intended, based on the API of pmc_capbilities().

The new PMC_OP_GETCAPS op needs to be added to the hwpmc(4) man page.

[mashtizadeh]

I'll update the docs for hwpmc in this patch. I'm still holding a few code patches that need to land to unblock a few other external collaborators. Once I get those out this week, I'll make my final pass on my hwpmc amd/ibs docs and push those too.

[mhorne]

I'll update the docs for hwpmc in this patch. I'm still holding a few code patches that need to land to unblock a few other external collaborators. Once I get those out this week, I'll make my final pass on my hwpmc amd/ibs docs and push those too.

Sounds great, many thanks.

[mhorne]

Thanks. I will merge today.

[mhorne]

Merged with some small minor tweaks to style (argument order) and to the commit message.

[mhorne]

As a follow-up I bumped PMC_VERSION_MINOR in sys/pmc.h. We don't maintain this carefully but it definitely makes sense here.