xl device doesn't work with ACPI enabled under -current and -stable

[Rongsheng Fang <rfang@xxxxxxxxxxxxx>]

Hi list,

I have a 3C905C network card (xl driver) which worked perfectly with 
ACPI enabled under 12/22/2004 -stable (ISO downloaded from 
ftp://ftp.dragonflybsd.org/iso-images/dfly-20041222-stable.iso.gz). But 
after I upgraded my system to -stable last week, xl doesn't work anymore 
with ACPI disabled (not packets can go out or come in).

Today I upgraded -stable to -current and rebuilt everything, but xl0 
still didn't work. Whenever I do any network related work (ping, ssh), 
the following kernel messages always came out:

xl0: watchdog timeout
intr 3 at 1811 hz, removing livelock limit
intr 3 at 103321 hz, livelocked! limiting at 20000 hz

Here is my network card:

xl0@pci2:0:0:   class=0x020000 card=0x00e31028 chip=0x920010b7 rev=0x78 
hdr=0x00
    vendor   = '3COM Corp, Networking Division'
    device   = '3C905C-TX Fast EtherLink for PC Management NIC'
    class    = network
    subclass = ethernet

rfang@xxxxxxxxxxxx /home/rfang $ uname -a
DragonFly pot.umuc.edu 1.1-CURRENT DragonFly 1.1-CURRENT #0: Wed Feb  2 
11:55:44 EST 2005     rfang@xxxxxxxxxxxx:/usr/obj/usr/src/sys/POT  i386

If I boot the system with ACPI disabled, then everything works again. 
Any ideas why?

I will provide more information if needed.

Thanks,

Rongsheng