Re: [lm-sensors] Problem with order of module loading

From: Jean Delvare <khali@linux-fr.org>
To: lm-sensors@vger.kernel.org
Subject: Re: [lm-sensors] Problem with order of module loading
Date: Wed, 04 Feb 2009 10:05:36 +0000	[thread overview]
Message-ID: <20090204110536.2ddaa6a4@hyperion.delvare> (raw)
In-Reply-To: <20090125021151.GE16739@paradise.net.nz>

Volker,

On Fri, 30 Jan 2009 17:23:36 +0100, Jean Delvare wrote:
> On Wed, 28 Jan 2009 09:06:28 +0100, Jean Delvare wrote:
> > I have discussed this a bit with Kay Sievers yesterday. He suggested
> > that we can use the modalias files in sysfs together with "modprobe -n"
> > to find out whether a loaded hwmon driver has been auto-loaded or not.
> > This would let us exclude kernel modules from /etc/sysconfig/lm_sensors
> > based on whether they auto-load rather than based on whether they were
> > loaded when sensors-detect was run. This should be way more robust than
> > my initial proposal, to a point where I think it would make sense to
> > give it a try.
> 
> Damn, it isn't as easy as I thought. Not all drivers follow the Linux
> device driver model to the letter. Actually, most hwmon drivers do not,
> because they create their own devices. Once such a driver is loaded, it
> appears to be autoloading (its devices have modalias strings that point
> to the driver) but in fact it is not. This fools my new code into
> thinking that pretty much all loaded hwmon drivers were autoloaded.
> 
> Thus I fear I will have to limit the scope of my autoloading detection
> code to PCI devices. At least this covers the k8temp driver, which is
> probably the one that causes the more trouble in practice.

I have finally committed a change which should address your issue:
  http://www.lm-sensors.org/changeset/5635

Basically, PCI and USB drivers which are auto-loaded on a given system
are no longer listed in /etc/sysconfig/lm_sensors. That way,
"rclm_sensors restart" will not unload and reload drivers which are
already present at boot time. This is the best approach from a
performance point of view, and it is also stable across reconfiguration
(running sensors-detect twice doesn't change the outcome.)

Please give a try to:
  http://www.lm-sensors.org/svn/lm-sensors/trunk/prog/detect/sensors-detect
and confirm that it solves your problem (k8temp should no longer be
listed, so the hwmon class device numbers should stay stable across
reboots.)

Thanks,
-- 
Jean Delvare

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