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Subject: Re: [PATCH] perf tools: get version from uname(2), not /proc
To: 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
References: <1444171996-24030-1-git-send-email-mmullins@twopensource.com>
 <20151007081854.GA20302@krava.landal.opennet> <5614D585.4010707@intel.com>
 <20151007171107.GA8650@whiteoak.sf.office.twttr.net>
From: Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
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Date: Thu, 8 Oct 2015 09:26:43 +0300
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On 07/10/15 20:11, Matt Mullins wrote:
> 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?

There is machine__is_host(), but what about /proc/sys/kernel/osrelease or
does that have the same problem?