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Re: autoloading of kernel modules in the udev area ?!

On Tue, Nov 13, 2007 at 02:23:58PM -0500, Bill Nottingham wrote:
> Hans de Goede (j w r degoede hhs nl) said: 
> > I'm basing my work on the i2c-tools specfile from Suse (one of the 
> > lm_sensors project lead works for Suse).
> >
> > This specfile contains in %files:
> > %attr(660, root, root) %dev(c, 89, 0) /lib/udev/devices/i2c-0
> >
> > This causes a /dev/i2c-0 char device to be effectively statically created. 
> > If I then also add the proper alias to modprobe.conf.dist, tools like 
> > i2cdump which need the i2c-dev kernel module loaded will automagically 
> > work.
> >
> > Is this ok / the best way todo this. Also I will be adding i2c-0 to i2c-3 
> > then, as there are many cases where there is more then 1 i2c bus (some 
> > motherboards have 2 on the board and many graphics / tv cards have i2c 
> > busses).
> What are the modules that live behind that device?
> > I just thought the same problem exists for non hardware backed devices like 
> > loop. Then I noticed that loop.ko is loaded, removing it and then trying a 
> > mount -o loop will cause mount to fail because it cannot find /dev/loop#.
> >
> > Who / what is responsible for loop.ko getting loaded by default, wouldn't 
> > it be better to use a similar trick with a static /dev entry and module 
> > autoloading, this would probably save both boottime and memory.
> loop is created by /etc/udev/makedev.d/50-udev.nodes.

The kernel now has DMI-based module autoloading, which I implemented
for the dcdbas module a few weeks ago[1].

Can you do something similar?

[1]http://www.mail-archive.com/mm-commits vger kernel org/msg28390.html

Matt Domsch
Linux Technology Strategist, Dell Office of the CTO
linux.dell.com & www.dell.com/linux

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