kern/89825: [em] Thinkpad T42 hangs when going to sleep when em is in kernel (regression)

Jacques Garrigue garrigue at
Fri Dec 2 02:30:06 GMT 2005

>Number:         89825
>Category:       kern
>Synopsis:       [em] Thinkpad T42 hangs when going to sleep when em is in kernel (regression)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Dec 02 02:30:02 GMT 2005
>Originator:     Jacques Garrigue
>Release:        6.0-RELEASE
Nagoya University
FreeBSD 6.0-RELEASE FreeBSD 6.0-RELEASE #1: Fri Dec  2 10:11:23 JST 2005     garrigue at  i386

The problem occurs on a Thinkpad T42, with Radeon M10 visual, Intel(R) PRO/1000 Network (em), Atheros 5212 wireless (ath).

When going to sleep under X11, using acpiconf -s3, the machine freezes.
The problem can be mitigated by setting hw.syscons.sc_no_suspend_vtswitch to 1, but I still observe freezes when going to sleep while accessing the disk.

The problem disappears completely when removing em from the kernel (no need for sc_no_suspend_vtswitch.)
It reappears when loading it as a kernel module.

There is no such problem using the generic kernel from 6.0-RC1 (which includes em)

The problem is still there in STABLE as of 2005-12-01.
On a Thinkpad T42, go to sleep under X11 without setting sc_no_suspend_vtswitch.
This might occur on other laptops using the em driver.
workaround: remove em from the kernel.

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