Re: Loading modules on demand with /sbin/hotplug

[Kay Sievers <kay.sievers@vrfy.org>]

On Wed, 2007-02-28 at 13:45 +0100, DervishD wrote:
>  * Kay Sievers <kay.sievers@vrfy.org> dixit:
> > If you find MODALIAS in the environment, just run /sbin/modprobe with
> > a RUN rule and almost all needed modules should get auto-loaded. There
> > are only a few exceptions for exotic subsystems.
> 
>     I've done this and now the systems hangs up at bootup. I can't find
> any information in any log, so I don't know the cause (probably modprobe
> caused some driver to load, which caused an udev event, which caused
> modprobe to run again, causing an infinite loop).

Start:
  udevd -n
and run:
  udevtrigger
and watch where it fails. Good luck! :)

>     At boot time I mount sysfs, load udevd, launch udevtrigger and
> udevsettle and after that, the rest of services of my system (I use my
> own init, so the boot scheme is a bit different, but not that much). The
> services are launched OK.
> 
>     In my rules file I have this:
> 
> KERNEL="pty*",      OPTIONS+="ignore_device"
> KERNEL="tty[a-z]*", OPTIONS+="ignore_device"
> 
> KERNEL="tty",  GROUP="tty"
> KERNEL="vcs",  GROUP="tty"
> KERNEL="vcsa", GROUP="tty"
> 
> KERNEL="hda1", GROUP="disk", MODE="660", SYMLINK+="root"
> KERNEL="hdb1", GROUP="disk", MODE="660", SYMLINK+="ubuntu"
> KERNEL="hdb2", GROUP="disk", MODE="660", SYMLINK+="swap"
> 
> KERNEL="full", MODE="222" 
> KERNEL="null", MODE="666"
> KERNEL="zero", MODE="444"
> 
> KERNEL="random", MODE="444"
> KERNEL="urandom", MODE="444"
> 
> SUBSYSTEM="usb_endpoint", OPTIONS+="ignore_device"
> 
> SUBSYSTEM="mem", GROUP="kmem"
> 
> SUBSYSTEM="usb_device", ATTRS{serial}="5B6B0990DFC6", NAME="pendrive"
> 
> #ACTION="add", ENV{MODALIAS}="?*", RUN="/sbin/modprobe $env{MODALIAS}"
> #ACTION="remove", ENV{MODALIAS}="?*", RUN="/sbin/modprobe -r $env{MODALIAS}"

Unloading modules may be possible - I don't know, and have no plans to
try this, because I don't think it makes a lot of sense.

> RUN+="/usr/sbin/hal &>> /tmp/hal.log"
> 
> -----------------------------
> 
>     The two commented lines are the ones that caused the problem. Any
> idea about the possible causes? If I move the modprobe command to my
> "hal" script (IT IS NOT freedesktop HAL, but my own script), the problem
> is the same: the system hangs as soon as the booting process finishes,
> and I don't have any evidence of modprobe being hung or whatever.
> 
>     I think I'm missing something VERY simple here, but I can't see
> what: have you any idea about which the problem may be? Should I delete
> the second commented line and don't unload modules on demand? May any of
> the commented lines be causing an infinite loop?

Maybe it's just a module that gets loaded and crashes the box, or a
failing module-init, that is causing a loop (like some platform modules
are known to do sometimes, because of misuse of MODALIAS).

Kay


-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys-and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CIDÞVDEV
_______________________________________________
Linux-hotplug-devel mailing list  http://linux-hotplug.sourceforge.net
Linux-hotplug-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel