IBM T42 freezes when going to sleep under X11

[George Hartzell]

Jacques Garrigue writes:
 > From: Jacques Garrigue <garrigue at math.nagoya-u.ac.jp>
 > > I've got a strange problem with my IBM T42 / Radeon M10 setup.
 > > 
 > > When using the 6.0-RELEASE kernel (including GENERIC), I cannot go to
 > > sleep when X11 is running: the machine freezes, display still on. I
 > > tried disabling DRI, but this does not seem to be the problem: I have
 > > no DRM anyway.
 > > 
 > > On the other hand, everything works fines with a 6.0-RC1 kernel.
 > > Was there a big change in between, such that I need to change my
 > > configuration?
 > 
 > I finally found the cause of my problems: there has been changes in
 > the em driver (Gb ethernet), such that the machine freezes when trying
 > to switch automatically from the X11 VT to the system console, before
 > going to sleep. The interaction is surprising, but clearly the problem
 > disappears when I remove "device em" from the kernel configuration,
 > and it reappears when I do "kldload if_em". Since I'm using only ath
 > (wireless) anyway, this is fine with me...
 > 
 > A previous partial solution suggested to me was to add
 >   hw.syscons.sc_no_suspend_vtswitch=1
 > to sysctl.conf, but this means the screen gets garbled and I have to
 > do the switch by hand anyway, which is a real pain.
 > Worse still: the machine would still freeze when going to sleep while
 > the disk is active.
 > 
 > The last step is to track down the bug in em, as it still seems to
 > be there in yesterday's STABLE.

I don't seem to have any problem with my T42p using a kernel compiled
on 11/29 11:21

My copy of if_em.c is:

/*$FreeBSD: src/sys/dev/em/if_em.c,v 1.65.2.8 2005/11/25 14:11:59 glebius Exp $*/

g.