Dell 5150 laptop and lost PS/2 touchpad

I'm not sure if this is a Dell BIOS problem, new interrupt
code problem, or PS/2 device driver problem.  The Dell
5150 laptop has a Synaptic touchpad, which fails to 
attach with the GENERIC kernel from RC1 and a custom
kernel from today sources.   A verbose boot shows:

atkbdc0: <Keyboard controller (i8042)> port 0x66,0x62,0x64,0x60 irq 1 on acpi0
atkbd0: <AT Keyboard> flags 0x1 irq 1 on atkbdc0
atkbd: the current kbd controller command byte 0065
atkbd: keyboard ID 0x41ab (2)
kbd0 at atkbd0
kbd0: atkbd0, AT 101/102 (2), config:0x1, flags:0x3d0000
psm0: current command byte:0065
psm0: the aux port is not functioning (-1).
 
Note, the psm0 messages are unchanged with/without acpi
and with/without apic compiled into the kernel.  After
looking through psm.c, I added

hint.psm.0.flags="0x1000"   # Ignore error in Aux Port test

to /boot/device.hints.   A verbose boot shows:

psm0: current command byte:0065
psm0: <PS/2 Mouse> flags 0x1000 irq 12 on atkbdc0
psm0: model Generic PS/2 mouse, device ID 0-00, 2 buttons
psm0: config:00001000, flags:00000000, packet size:3
psm0: syncmask:c0, syncbits:00

and moused(8) seems to be happy.  I haven't looked closer
at the problem, yet.  However, with the impending release
of 5.2, an erratum may be in order.

-- 
Steve