UDEV hangs on boot

[Jerry Feldman]

I'm trying to get one of our servers to boot with 64GB. The kernel
boots, but "starting UDEV" hangs.
This is an Intel whitebox with a Supermicro X7DB8+ MB currently flashed
at BIOS 2.1a. The memories are 16 4GB DIMMS (Kingston) that have been
certified by Supermicro. This occurs on both RHEL 5.2 and RHEL 5.3. I've
got 3 other nearly identical servers running successfully. I've changed
the PCI hole from 256MB to 1GB to 2GB.. This is a pulldown in the BIOS
and I only have these choices (actually 512 also).

I've been doing more checking. Note that in RHEL you can turn on udev
debugging as a kernel argument (udevdebug).
I've determined that the culprit is udevsettle that resides in
/sbin/start_udev. This is a hard hang, and setting a timeout value does
nothing (eg. udevtimeout=180). With udevdebug set I have a number of
messages showing that some of the udev tasks have completed, but I have
not been able to track them to a device. The only way to access the
script is to boot into the rescue. I've also determined that removing
the additional 2 SATA drives makes no difference. I've disabled both the
serial, parallel and floppy ports in the BIOS. I've also set the noapic
and acpi=off kernel flags. Additionally, I've modified the
/sbin/start_udev script replacing udevsettle with /bin/sleep, which also
hangs.
Setting the udevdebug flag causes a lot of messages to scroll by on the
screen, but I don't see anything that would be a red flag. Additionally,
I've set modprobedebug. This shows that there are several modules that
have FATAL failures because of no file found.
If I comment out /sbin/start_udev in rc.sysinit, I do get a somewhat
working system, with no graphics (which is ok).

Some history, is that we were fiddling around and placed 1 1GB DIMM in
each bank and we were able to boot.
Additionally, we boot into the rescue with no problems.

One thing I am going to try on Monday is possibly trying to run a live
CD (possibly Fedora), but in the long run I need to run either RHEL 5.2
(preferred) or RHEL 5.3.

Just one more tidbit. I had another system that was using 16 1GB DIMMS,
when I upgraded that, it had the same problem, but after I rebooted it,
I was unable to get it back up, and when I did it would not recognize
the 4GB DIMMS, but since I had another dead system (power supply and
power switch), we moved the memories to that system.

Additionally, I di occasionally receive a checksum error on the BIOS
(both machines), but not on every boot.

-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix
PGP key id: 537C5846
PGP Key fingerprint: 3D1B 8377 A3C0 A5F2 ECBB  CA3B 4607 4319 537C 5846


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