Date: Mon, 17 Mar 2008 21:33:30 +0100
From: Jean Delvare <khali@linux-fr.org>
To: Gabriel C <nix.or.die@googlemail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Zhang Rui <rui.zhang@intel.com>, Len Brown <len.brown@intel.com>,
       Gabriel C <crazy@frugalware.org>
Subject: Re: Linux 2.6.25-rc6
Message-ID: <20080317213330.27d47382@hyperion.delvare>
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On Mon, 17 Mar 2008 20:35:24 +0100, Gabriel C wrote:
> Jean Delvare wrote:
> > Hi Gabriel,
> > 
> > On Mon, 17 Mar 2008 15:34:04 +0100, Gabriel C wrote:
> >> Linus Torvalds wrote:
> >>
> >>> Zhang, Rui (2):
> >>>       thermal: fix generic thermal I/F for hwmon
> >> That commit broke lmsensros here ( found by bisect ). 
> >> ...
> >>
> >> Can't access procfs/sysfs file
> >> Kernel interface access error
> >> For 2.6 kernels, make sure you have mounted sysfs and libsensors
> >> was compiled with sysfs support!
> >>
> >> ...
> >>
> >> Of course proc and sysfs is mounted and the lib has that support :)
> > 
> > This has been reported as:
> > http://bugzilla.kernel.org/show_bug.cgi?id=10259
> > https://bugzilla.redhat.com/show_bug.cgi?id=437637
> > 
> > The generic thermal zone device does something which is not
> > fundamentally incorrect but that libsensors doesn't expect, and
> > unfortunately libsensors was not made robust enough and dies instead of
> > just ignoring the new unexpected device. libsensors 2.10.x is already
> > fixed in lm-sensors' SVN [1] and a tentative patch is available for
> > libsensors 3.0.x [2], however I am worried that kernel 2.6.25 will be
> > released before any new version of lm-sensors so pretty much every user
> > of lm-sensors will hit the problem if they upgrade to the new kernel.
> > For this reason, I think we really should let the new generic thermal
> > zone driver build as a module, and make it's hwmon support optional and
> > disabled by default for 2.6.25 [3]. This will help mitigate the risk of
> > massive breakage and complaints.
> > 
> > [1] http://www.lm-sensors.org/changeset/5147
> > [2] https://bugzilla.redhat.com/attachment.cgi?id=298270
> > [3] http://lists.lm-sensors.org/pipermail/lm-sensors/2008-March/022724.html
> > 
> 
> 
> Hmm , ok but then the situation is even worse.
> 
> Why something *known* to break _all_ existing lmsensors setups out there 
> is being pushed that late in game ?

I completely agree that it shouldn't have been included that late in
the release cycle, in particular when it obviously received no testing
at all (it breaks all versions of lm-sensors.)

The reason why it was merged is that some people feared that
application authors would add support for the new thermal zone
interface (/sys/class/thermal) quickly instead of waiting for the same
information to be exported through the standard hwmon interface
(/sys/class/hwmon) which libsensors supports. This now appears to be a
very small problem compared to breaking lm-sensors for all users out
there.

> IMO that should be just reverted from 2.6.25 and pushed again in the next merge window.

This would be totally fine with me, yes.

-- 
Jean Delvare
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