[arch-dev-public] Module blacklisting

[Aaron Griffin]

On Fri, Feb 22, 2008 at 5:56 PM, eliott <eliott at cactuswax.net> wrote:
> On 2/22/08, Aaron Griffin <aaronmgriffin at gmail.com> wrote:
>  > Ok, guys - honest question. Because udev is being a big pain in the
>  >  ass with the way we do module blacklisting, we might want to
>  >  reevaluate it.
>  >
>  >  Right now we support blacklisting of modules in rc.conf, in addition
>  >  to a kernel param disablemodules=x,y,z
>  >
>  >  Udev autoloading is controlled by MOD_AUTOLOAD and the load_modules
>  >  kernel param.
>  >
>  >  We *can* use modprobe based blacklisting here, but we lose the above
>  >  items. blacklisting will be controlled only by /etc/modprobe.conf (and
>  >  modprobe.d/*) and we lose the ability to shut it off via rc.conf.
>  >
>  >  What do we gain? Speed and simplicity. No extraneous scripts to handle
>  >  this stuff, and all that jazz.
>  >
>  >  This is how fast this script was when I originally wrote it:
>  >  http://img.phraktured.net/other/udev_modules_boot.png
>  >  Now it apparently takes 3 times as long due to all the added blacklisting cruft
>  >
>  >  What do we lose? Robustness.
>  >  See below for an explanation of the blacklist changes
>
>  I thin modprobe.conf would probably be 'cleaner' and 'closer to home'.
>  It would probably be a little less 'classic arch', as it moves things
>  away from rc.conf instead of into it. It might be the right thing to
>  do though..not sure.

That's about where I am right now. It feels cleaner, but begins moving
things out of rc.conf, which is un-Archy. I dunno, I'm hoping to hear
other people's opinions on this, as I'm holding off pushing out a udev
with start_udev still in it until we decide what to do here... anyone
have a strong opinion?

>  I do have one concern though. How would this effect mkinitcpio, and
>  excluding modules via grub at boot time (whether from an install cd or
>  from a real boot and with an initrd)?

That's harder. But we have two options. Firstly, the initramfs udev
can have different sets of rules, there's nothing wrong with that.
Secondly, before starting udev in the initramfs, we can do something
like:

   for x in $disablemodules; do
      echo "blacklist $x" >> /etc/modprobe.conf
   done

/me shrugs