[arch-general] Incorporate udev rules in initrd

[Dave Reisner]

On Sun, Jan 13, 2013 at 02:21:01PM +0000, Rodrigo Rivas wrote:
> On Sat, Jan 12, 2013 at 10:55 PM, Christoph Vigano <mail at cvigano.de> wrote:
> 
> > On 31.12.2012 11:00, Rodrigo Rivas wrote:
> > > On Mon, Dec 31, 2012 at 8:37 AM, Christoph Vigano <mail at cvigano.de>
> > wrote:
> > >
> > >>
> > >> How can I tell mkinitcpio to include a custom udev rule? Do I need to
> > >> write a hook for that? How can a hook for this look like?
> > >
> > >
> > > AFAIK, using FILES="path-to-udev-rule-file" should be enough. The udev
> > > binaries and basic rules are already there, so adding the custom rule to
> > > the image should make it work automagically.
> > >
> > > HTH
> > > --
> > > Rodrigo
> > >
> >
> > Sadly, that did not work although the file containing the rule is inside
> > the initrd (verified with lsinitcpio).
> >
> > Any other idea how to debug this?
> >
> 
> Well... an ugly hack I did to debug the initrd is, if you use grub:
> 1. In the grub menu press 'e' to edit the boot commands.
> 2. Remove the 'root=whatever' or change it so something non-existant.
> 3. Run the boot commands with F10.
> 
> This way the initramfs will not mount the root filesystem and will drop to
> a emergency shell. It will run with the initramfs mounted at '/', so you
> can use it to debug your problem. Note that you still can mount the real
> root into, for example, '/mnt' and copy or use any tool or file you need
> that is not available in initramfs (eg 'udevadm').
> 
> Yes, it is a hack, but I don't know a proper way to do it. Other distros,
> such as Ubuntu, have a 'debug=<breakpoint>' option to do this kind of
> things. But, hey, it works, I even used it once to convert the root
> filesystem from ext4 to btrfs without an additional boot device 8-).
> 
> -- 
> Rodrigo

mkinitcpio's manpage documents a 'break' variable which does this
sanely.