freebsd stable - Jul 2012 - Regression in stable for ThinkPad T520 with Intel GPU (Sandybridge) between June 22 and July 18

I will shortly spend a bit of time tracking down the breakage more
closely, but my 9-Stable system of June 22 runs fine. After an update
on about July 10, I noted that it would hang after Xorg was started,
but usually worked. After an upgrade to July 18, my system could no
longer start Gnome. It would start Xorg and Gnome would start
normally, getting many apps started, but about 10 seconds after the
wallpaper loaded, the system would freeze solid. No network access and
no response to mouse or keyboard.

I have looked into commits to 9-STABLE during the time at issue and
very little seems to have changed due to the pre-9.1 freeze.
Similarly, nothing much has changed in any of the X11 ports.

This really smells a lot like a race condition. I can trigger the same
behavior by enabling VT-x (not VT-d) in BIOS. In all cases where it
was intermittent, if my desktop completed startup, the system runs
fine until re-booted. This is probably the primary reason I might not
have realized that there was a problem as I don't boot the system
often except when traveling, which I was between July 1 and July 6 and
again July 18 when the system died.

Any idea what I might try looking at?
-- 
R. Kevin Oberman, Network Engineer
E-mail: kob6558@gmail.com

On Tue, 2012-07-24 at 18:35 -0700, Kevin Oberman wrote:
> I will shortly spend a bit of time tracking down the breakage more
> closely, but my 9-Stable system of June 22 runs fine. After an update
> on about July 10, I noted that it would hang after Xorg was started,
> but usually worked. After an upgrade to July 18, my system could no
> longer start Gnome. It would start Xorg and Gnome would start
> normally, getting many apps started, but about 10 seconds after the
> wallpaper loaded, the system would freeze solid. No network access and
> no response to mouse or keyboard.
> 
> I have looked into commits to 9-STABLE during the time at issue and
> very little seems to have changed due to the pre-9.1 freeze.
> Similarly, nothing much has changed in any of the X11 ports.
> 
> This really smells a lot like a race condition. I can trigger the same
> behavior by enabling VT-x (not VT-d) in BIOS. In all cases where it
> was intermittent, if my desktop completed startup, the system runs
> fine until re-booted. This is probably the primary reason I might not
> have realized that there was a problem as I don't boot the system
> often except when traveling, which I was between July 1 and July 6 and
> again July 18 when the system died.
> 
> Any idea what I might try looking at?

Oh good, its not just me.  I note that this is happens when I'm not
hardwired in at my docking station as the system doesn't get a routeable
IP addr, until much later if on wireless.

When watching the system boot, I think I might ctrl-c the sendmail
startup or something when it starts to keep this from happening.

Sean