From: Andi Kleen <ak@linux.intel.com>
To: Greg KH <greg@kroah.com>, kan.liang@linux.intel.com
Cc: peterz@infradead.org, mingo@redhat.com,
linux-kernel@vger.kernel.org, eranian@google.com,
namhyung@kernel.org, acme@kernel.org, jolsa@redhat.com
Subject: Re: [PATCH 2/7] perf: Create a symlink for a PMU
Date: Thu, 24 Jun 2021 07:24:31 -0700 [thread overview]
Message-ID: <d25a0556-325f-9af0-a495-b9f222d63e10@linux.intel.com> (raw)
In-Reply-To: <YNQckpOuw80uCUa1@kroah.com>
> But first off, why is this symlink suddenly needed? What is so special
> about this new hardware that it breaks the existing model?
The driver can be in two modes:
- Driver fully knows the hardware and puts in the correct Linux names
- Driver doesn't know the hardware but is in a fallback mode where it
only looks at a discovery table. There we don't have the correct names,
just an numeric identifier for the different hardware sub components.
In the later mode the numeric identifier is used in sysfs, in the former
case the full Linux name. But we want to keep some degree of Linux user
space compatibility between the two, that is why the full mode creates a
symlink from the "numeric" name. This way the (ugly) identifiers needed
for the fallback mode work everywhere.
-Andi
next prev parent reply other threads:[~2021-06-24 14:24 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-24 1:22 [PATCH 0/7] perf: Add Sapphire Rapids server uncore support kan.liang
2021-06-24 1:22 ` [PATCH 1/7] driver core: Add a way to get to bus devices kset kan.liang
2021-06-24 5:41 ` Greg KH
2021-06-24 1:22 ` [PATCH 2/7] perf: Create a symlink for a PMU kan.liang
2021-06-24 5:48 ` Greg KH
2021-06-24 14:24 ` Andi Kleen [this message]
2021-06-24 14:29 ` Greg KH
2021-06-24 15:24 ` Andi Kleen
2021-06-24 15:31 ` Greg KH
2021-06-24 17:07 ` Liang, Kan
2021-06-24 17:35 ` Greg KH
2021-06-24 17:49 ` Andi Kleen
2021-06-25 5:18 ` Greg KH
2021-06-25 5:17 ` Greg KH
2021-06-24 17:28 ` Andi Kleen
2021-06-25 5:19 ` Greg KH
2021-06-25 14:22 ` Andi Kleen
2021-06-25 14:38 ` Greg KH
2021-06-25 14:49 ` Andi Kleen
2021-06-25 15:03 ` Liang, Kan
2021-06-25 15:44 ` Andi Kleen
2021-06-25 15:57 ` Liang, Kan
2021-06-25 16:18 ` Liang, Kan
2021-06-27 11:02 ` Greg KH
2021-06-27 16:30 ` Andi Kleen
2021-06-28 6:55 ` Greg KH
2021-06-28 15:00 ` Andi Kleen
2021-06-24 1:22 ` [PATCH 3/7] perf/x86/intel/uncore: Create a symlink for an uncore PMU kan.liang
2021-06-24 5:44 ` Greg KH
2021-06-24 1:22 ` [PATCH 4/7] perf/x86/intel/uncore: Add Sapphire Rapids server support kan.liang
2021-06-24 1:22 ` [PATCH 5/7] perf/x86/intel/uncore: Factor out snr_uncore_mmio_map() kan.liang
2021-06-24 1:22 ` [PATCH 6/7] perf/x86/intel/uncore: Support free-running counters on Sapphire Rapids server kan.liang
2021-06-24 1:22 ` [PATCH 7/7] perf/x86/intel/uncore: Fix invalid unit check kan.liang
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