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Date: Wed, 7 Oct 2015 10:11:08 -0700
From: Matt Mullins <mmullins@twopensource.com>
To: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>, acme@kernel.org,
        Vinson Lee <vlee@twopensource.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
        Kan Liang <kan.liang@intel.com>, Andi Kleen <ak@linux.intel.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf tools: get version from uname(2), not /proc
Message-ID: <20151007171107.GA8650@whiteoak.sf.office.twttr.net>
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	Jiri Olsa <jolsa@redhat.com>, acme@kernel.org,
	Vinson Lee <vlee@twopensource.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Ingo Molnar <mingo@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Kan Liang <kan.liang@intel.com>, Andi Kleen <ak@linux.intel.com>,
	linux-kernel@vger.kernel.org
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On Wed, Oct 07, 2015 at 11:19:17AM +0300, Adrian Hunter wrote:
> On 07/10/15 11:18, Jiri Olsa wrote:
> > On Tue, Oct 06, 2015 at 03:53:14PM -0700, Matt Mullins wrote:
> >> Tools in kmod (e.g. modprobe) compose the module path from the release
> >> from uname(2).  Because we use the UNAME26 personality, we need perf to
> >> find modules located at the same path as the system tools.
> > 
> > I guess it's easy to google this up, but could you
> > please state in the changelog what's the difference
> > between the current version and the UNAME26 one?
> > 
> > Also state (and check) this change wouldn't affect other
> > parts of the code that use this version (if there's any).

This is the only caller of get_kernel_version.

> Isn't the machine root dir for guests? uname() won't work for them.

Aye, this would break --guestmount.  Would it make sense to use uname()
iff root_dir is the empty string, or is that too much special-casing for
good taste?