Bug 61851

Created attachment 109161 [details]
Dmesg output for kernel 3.10, showing hang

A couple of weeks ago I installed Debian's linux-image-3.10-2-amd64 package on my old HP dc5800 small form factor desktop running Debian testing.

As you can see from the attached dmesg output, the kernel freezes for about 10 minutes at a specific point during the boot process. The computer does not respond to any key strokes during this time. The long but temporary freeze is completely reproducible; it happens on every boot/reboot at exactly the same place. Once the kernel has finally booted it seems to work fine.

For comparison, I have also attached the dmesg output obtained using the kernel from linux-image-3.9-1-amd64, which does not freeze.

I googled the problem and found a few posts (see, e.g., http://blog.subaquatic.net/archives/hp-dc5800-linux-boot-fix/) suggesting that booting with "pci=nommconf" cures the problem. This works, but the posts mentioning it are several years old and I have never had any trouble with previous Debian kernels.

Quite by accident, I discovered that removing the word "quiet" from the kernel command line also cures the problem. This is very strange.

I then tested two different builds of kernel 3.11 downloaded direct from kernel.org, one using the standard Debian config (attached as "config-debian") and the other a simpler config obtained by starting from the "make xconfig" default and switching off some things I was fairly sure I did not need (copy attached as "config-simpler"). The version using the Debian config behaves exactly like the Debian 3.10 kernel package; the version using the simpler config never hangs on boot.

I reported this problem as Debian bug #719627, but Ben Hutchings of the Debian kernel team asked me to report it here too. I am happy to do so, but doubt I have the technical knowledge to help track down what is wrong.