On 05/15/2011 01:32 PM, Tom Gundersen wrote:
On Sun, May 15, 2011 at 8:19 PM, Nix<nix@xxxxxxxxxxxxx> wrote:
I know that you're not supposed to rely on 'udevadm settle' anymore, but
I rely on it across the board for systems with root filesystems that
aren't expected to move around (i.e. all of them), because massively
reengineering working systems' boot processes is generally considered a
bad thing. And it's stopped working. Given how many things expect /dev
to be populated, this has fairly serious effects.
I can be certain that as of somewhere between udev 164 and 167, 'udevadm
settle' has stopped waiting for block devices to appear (though I
suspect others have vanished too). I'm booting udev as recommended in
the release notes, via
udevd --daemon
udevadm trigger --action=add --type=subsystems
udevadm trigger --action=add --type=devices
udevadm settle
We are doing the same on Arch and today I started seeing bug reports
(after the upgrade to udev 168). So here are my two cents:
Most of the time the problem seems to be related to LVM, but I have
also seen regular block devices having problems. As would be expected
using devtmpfs greatly reduces (if not eliminates) the problem. My
guess was (like Nix said) that "udevadm settle" is somehow broken.
Some related bug reports:
Arch:<https://bugs.archlinux.org/task/24288>,
Debian:<http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=624010>.
Cheers,
Tom
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Just to add a "me too" regarding regular block devices. First noticed
with 168, coming from 165. /dev was tmpfs and swap is /dev/sda3 and
mounted immediately after udevadm --settle. Kernel is 2.6.36.2. In
addition to the udev change, I added the /run mount point to the mix
(started very early, directly in rc before any scripts are run). Moving
to devtmpfs 'fixed' it for me, but that was because devtmpfs has the raw
sd* nodes, as explained to me by another dev. If I flip to use by-id, it
breaks again. I plan to go back and see exactly where stuff broke, but
haven't had the time just yet, more pressing issues. Probably a
Wednesday evening project (CDT).
-- DJ Lucas
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