From: Peter Zijlstra <peterz@infradead.org>
To: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, Robert Richter <rric@kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Mike Galbraith <efault@gmx.de>, Paul Mackerras <paulus@samba.org>,
Stephane Eranian <eranian@google.com>,
Andi Kleen <ak@linux.intel.com>,
kan.liang@intel.com, adrian.hunter@intel.com, acme@infradead.org
Subject: Re: [PATCH v5 12/20] x86: perf: intel_pt: Intel PT PMU driver
Date: Fri, 24 Oct 2014 15:48:00 +0200 [thread overview]
Message-ID: <20141024134800.GC21513@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <87tx2td2rt.fsf@ashishki-desk.ger.corp.intel.com>
On Fri, Oct 24, 2014 at 04:18:46PM +0300, Alexander Shishkin wrote:
> Peter Zijlstra <peterz@infradead.org> writes:
> Ah, I see what you mean. The main point of this whole reserved region
> proposal is that one shouldn't have to update one's kernel to enable new
> PT packets by doing -e intel_pt/config=0xf00d/, if one is CAP_SYS_ADMIN.
>
> > No need to probe in that case. That is the same thing we do for all
> > unenumerated model specific things.
>
> They are, actually, enumerated, we just want to be able to enable them
> before they are. If the driver is aware of feature X, it can test for it
> in CPUID and allow/disallow it based on that.
If you've got hardware that 'exposes' functionality not enumerated in
CPUID you have the capability of modifying the kernel.
And while it might seem like a cute feature when you have early
hardware, that is no reason to make the code horrible. Either just patch
your firmware such that CPUID reports the right bits for your hardware
or frob the kernel.
next prev parent reply other threads:[~2014-10-24 13:48 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-13 13:45 [PATCH v5 00/20] perf: Add infrastructure and support for Intel PT Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 01/20] perf: Add data_{offset,size} to user_page Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 02/20] perf: Add AUX area to ring buffer for raw data streams Alexander Shishkin
2014-10-22 12:35 ` Peter Zijlstra
2014-10-23 3:05 ` Frederic Weisbecker
2014-10-13 13:45 ` [PATCH v5 03/20] perf: Support high-order allocations for AUX space Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 04/20] perf: Add a capability for AUX_NO_SG pmus to do software double buffering Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 05/20] perf: Add a pmu capability for "exclusive" events Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 06/20] perf: Add AUX record Alexander Shishkin
2014-10-22 13:26 ` Peter Zijlstra
2014-10-22 14:18 ` Alexander Shishkin
2014-10-22 15:07 ` Peter Zijlstra
2014-10-13 13:45 ` [PATCH v5 07/20] perf: Add api for pmus to write to AUX area Alexander Shishkin
2014-10-22 14:02 ` Peter Zijlstra
2014-10-22 14:14 ` Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 08/20] perf: Support overwrite mode for " Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 09/20] perf: Add wakeup watermark control to " Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 10/20] x86: Add Intel Processor Trace (INTEL_PT) cpu feature detection Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 11/20] x86: perf: Intel PT and LBR/BTS are mutually exclusive Alexander Shishkin
2014-10-22 14:15 ` Peter Zijlstra
2014-10-24 7:47 ` Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 12/20] x86: perf: intel_pt: Intel PT PMU driver Alexander Shishkin
2014-10-22 14:17 ` Peter Zijlstra
2014-10-22 14:20 ` Peter Zijlstra
2014-10-24 7:49 ` Alexander Shishkin
2014-10-24 11:26 ` Peter Zijlstra
2014-10-24 12:01 ` Alexander Shishkin
2014-10-22 14:23 ` Peter Zijlstra
2014-10-22 14:27 ` Peter Zijlstra
2014-10-24 7:50 ` Alexander Shishkin
2014-10-22 14:32 ` Peter Zijlstra
2014-10-31 13:13 ` Alexander Shishkin
2014-11-04 15:57 ` Peter Zijlstra
2014-11-11 11:24 ` Alexander Shishkin
2014-11-11 13:20 ` Peter Zijlstra
2014-11-11 14:17 ` Alexander Shishkin
2014-10-22 14:34 ` Peter Zijlstra
2014-10-24 7:52 ` Alexander Shishkin
2014-10-22 14:45 ` Peter Zijlstra
2014-10-24 8:22 ` Alexander Shishkin
2014-10-24 11:51 ` Peter Zijlstra
2014-10-24 12:13 ` Alexander Shishkin
2014-10-24 13:02 ` Peter Zijlstra
2014-10-24 13:18 ` Alexander Shishkin
2014-10-24 13:48 ` Peter Zijlstra [this message]
2014-10-22 14:49 ` Peter Zijlstra
2014-10-22 15:11 ` Peter Zijlstra
2014-10-22 14:55 ` Peter Zijlstra
2014-10-24 7:59 ` Alexander Shishkin
2014-10-22 15:14 ` Peter Zijlstra
2014-10-24 7:59 ` Alexander Shishkin
2014-10-22 15:26 ` Peter Zijlstra
2014-10-13 13:45 ` [PATCH v5 13/20] x86: perf: intel_bts: Add BTS " Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 14/20] perf: add ITRACE_START record to indicate that tracing has started Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 15/20] perf: Add api to (de-)allocate AUX buffers for kernel counters Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 16/20] perf: Add a helper for looking up pmus by type Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 17/20] perf: Add infrastructure for using AUX data in perf samples Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 18/20] perf: Allocate ring buffers for inherited per-task kernel events Alexander Shishkin
2014-10-23 12:38 ` Peter Zijlstra
2014-10-24 7:44 ` Alexander Shishkin
2014-10-30 8:43 ` Peter Zijlstra
2014-10-30 10:20 ` Alexander Shishkin
2014-10-30 13:31 ` Arnaldo Carvalho de Melo
2014-10-13 13:45 ` [PATCH v5 19/20] perf: Allow AUX sampling for multiple events Alexander Shishkin
2014-10-13 13:45 ` [PATCH v5 20/20] perf: Allow AUX sampling of inherited events Alexander Shishkin
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