Created attachment 109171 [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 odd.

I then tested two different builds of kernel 3.11 from kernel.org, one
using the standard Debian config (attached as "config-debian") and the
other a simpler config I made up myself (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 skills to help track down what is wrong.

The kernel.org bugzilla web interface only seems to allow one attachment,
so I have tarred the four files mentioned above together.