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Dr. Arbeitslos
Apprentice
Joined: 13 Aug 2005
Posts: 152
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 Posted: Tue Apr 10, 2007 8:23 am Post subject: How to prevent loading of some modules? |
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hi,
if my comp starts up, some modules are loaded autoamatically ( by kernel itself or udev or...? ).
is there a way to prevent this for designated modules? e.g. "evbug" is loaded by udev (it announces it) and spams my /var/log/messages all the time.
I know how to remove it from kernel configuration, but that is not what i'm asking for (maybe I need it in future).
I also know how to load modules that are not loaded automatically (by /etc/modules.autoload.d/kernel-2.6), but is there also a way for the opposite (preventing modules from automatic loading)?
thanks for your help. |
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PaulBredbury
Watchman
Joined: 14 Jul 2005
Posts: 7310
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| Posted: Tue Apr 10, 2007 8:44 am Post subject: |
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Use /etc/modprobe.d/blacklist
| Code: | # Used to stop udev from loading modules.
# http://bugs.gentoo.org/show_bug.cgi?id=130766
# Run "modules-update" after changing.
blacklist evbug |
Edit: Fixed my confusion over modules and modprobe 
Last edited by PaulBredbury on Tue Apr 10, 2007 11:05 am; edited 1 time in total |
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Dr. Arbeitslos
Apprentice
Joined: 13 Aug 2005
Posts: 152
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| Posted: Tue Apr 10, 2007 10:44 am Post subject: |
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Thank you PaulBredbury.
after reading
https://bugs.gentoo.org/show_bug.cgi?id=130766
and googling a bit it seems blacklisting is now done inside
/etc/modprobe.d/blacklist.
both files are working for me, but modules-update after adding /etc/modules.d/blacklist gave me an error message (and worked anyway). |
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PaulBredbury
Watchman
Joined: 14 Jul 2005
Posts: 7310
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| Posted: Tue Apr 10, 2007 11:10 am Post subject: |
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You're right about modprobe.d
To fix the silly error message:
| Code: | $ modules-update
* Updating /etc/modprobe.conf ...
* Warning: could not generate /etc/modprobe.conf! [ !! ]
* Updating /etc/modprobe.conf by hand ...
* Warning: could not generate /etc/modprobe.conf! [ !! ]
* Updating modules.dep ... [ ok ] |
Run:
| Code: | cd /etc
mv modules.conf modules.conf-bak
mv modprobe.conf modprobe.conf-bak
modules-update |
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dch24
Tux's lil' helper
Joined: 15 Feb 2007
Posts: 99
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| Posted: Wed Jul 11, 2007 11:06 pm Post subject: |
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This post describes the difference between 'blacklist' and what you are trying to do:
| Joey Hess wrote: | Package: module-init-tools
Version: 3.3-pre11-1
Severity: normal
If you look up "module blacklist" or "modprobe blacklist" or "udev
blacklist" in google, the results are various and mostly wrong,
outdated, or distro-specific.
modprobe.conf(5)'s docuentation of the blacklist command is ok, but
still leaves open the question of how to really blacklist a module so
modprobe won't load it at all.
Expecting a regular user to read the documentation of the install
command and think of "install module /bin/true" as the way to turn off
loading of a module is probably expecting too much of many users. It's
even expecting too much of some developers; I did not make this
connection on my first or second reading of the man page, and did not
think of it until I saw it mentioned on the web[1].
Since module-init-tools has a FAQ, I thought it might help to document
how to blacklist a module there.
Something like:
| Code: | Q) How do I prevent udev or modprobe from loading a module?
A) Putting this in a file in /etc/modprobe.d/ will guarantee that modprobe
never loads a module (in this case the PC speaker driver), but it not
necessarily the best approach in all circumstances:
install pcspkr /bin/true
If there are two modules that can both support the same device, and
the wrong module is being used, the above won't help; it will prevent
the wrong module from being loaded, but will not load the correct
module. In this case, you should instead use the blacklist command:
blacklist eepro100
This will prevent the older eepro100 module from being used, and
allow the newer e100 module to be loaded instead.
See the modprobe.conf(5) man page for details. |
If you add this you might also want to add a pointer to it to
/etc/modprobe.d/blacklist
--
see shy jo
[1] http://www.beranger.org/index.php?page=3k&fullarticle=2256
Currently the 20th hit for "udev blacklist" |
In other words, this will disable it at the modprobe level. (Then when you want to use it, just add a # to comment out the line, and run update-modules and modprobe it in. Not exactly what you wanted, but ...)
There's a good discussion in the bug #130766 thread about using /etc/conf.d/rc to disable services (so the modules are still loaded but the service doesn't get started) and about the security hole opened by autoloading evbug. The bug is closed because "Comment #46 From Matthias Schwarzott 2007-02-13 00:16:10 0000 [reply] udev-104-r11 (and -r10) implement the wrapper-based blacklisting, by using the blacklist-lines from modprobe.conf" but I have not seen documentation or an example of how this works. |
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