udev and initramfs

[Tom H]

On Thu, Dec 9, 2010 at 3:52 AM, Loïc Grenié <loic.grenie at gmail.com> wrote:
>
>    I have a problem and I do not understand why... From udev (lucid: 151-12.2)
>  I have in file /lib/udev/rules.d/60-persistent-storage.rules:
>
> [snip]
> # probe filesystem metadata of optical drives which have a media inserted
> KERNEL=="sr*", ENV{ID_CDROM_MEDIA}=="?*",
> ENV{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}=="?*",
> IMPORT{program}="/sbin/blkid -o udev -p -u noraid -O
> $env{ID_CDROM_MEDIA_SESSION_LAST_OFFSET} $tempnode"
> # single-session CDs do not have ID_CDROM_MEDIA_SESSION_LAST_OFFSET
> KERNEL=="sr*", ENV{ID_CDROM_MEDIA}=="?*",
> ENV{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}=="",
> IMPORT{program}="/sbin/blkid -o udev -p -u noraid $tempnode"
>
> # probe filesystem metadata of disks
> KERNEL!="sr*", IMPORT{program}="/sbin/blkid -o udev -p $tempnode"
> [snip]
>
>  and in file /usr/share/initramfs-tools/hooks/udev:
>
> [snip]
> copy_exec /sbin/blkid /lib/udev
> [snip]
>
>   Thus blkid ends in /lib/udev on the initramfs. The consequence I have
>  is that the system won't reboot because blkid is not executed (because
>  udev will look for it in /sbin and it's not there) and I thus do not have the
>  links created in /dev/disk/by-uuid.
>
>    What I'd love to understand is why I seem to be the *only one* with
>  that problem. Are there somehow
>  /etc/udev/rules.d/60-persistent-storage.rules on "normal" systems
>  with a different call to blkid ? Does anybody understand what I have
>  modified to break my system ? How does your kernel command-line
>  look like (cat /proc/cmdline) ?

If you unpack your initrd, you'll find that "/sbin/blkid" exists.

I'm not sure whether "/lib/udev/blkid" is used by the initrd scripts
so I can only explain its existence as a historical twist because
that's where vol_id used to be.