port-amd64/39951: amd64 freezes due to interrupt storm on int19

[ghen%telenet.be@localhost]

>Number:         39951
>Category:       port-amd64
>Synopsis:       amd64 won't boot SMP due to interrupt storm on int19
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Nov 18 14:50:00 +0000 2008
>Originator:     Geert Hendrickx
>Release:        NetBSD 5.0_BETA
>Organization:
>Environment:
System: NetBSD boris.ghen.be 5.0_BETA NetBSD 5.0_BETA (GENERIC) #0: Sun Nov 16 
05:22:22 CET 2008 
ghen%boris.ghen.be@localhost:/scratch/netbsd/netbsd-5/obj/sys/arch/amd64/compile/GENERIC
 amd64
Architecture: x86_64
Machine: amd64
>Description:
A Dell Inspiron 530 pc hangs at boot due to an interrupt storm on int 19.
This is with NetBSD-current and 5.0_STABLE, both i386 and amd64 ports.

Here are the last few output lines from a hanging MPVERBOSE kernel:

ioapic0: int1 68<vector=68,delomde=0,dest=0> 0<target=0>
pckbc0: using irq 1 for kbd slot
wskbd0 at pckbd0: console keyboard, using wsdisplay0
fdc0 at isa0 port 0x3f0=0x3f7 irq 6 drq 2
ioapic0: int6 69<vector=69,delmode=0,dest=0> 0<target=0>
timecounter: Timecounter "clockinterrupt" frequency 100 Hz quality 0
timecounter: Timecounter "TSC" frequency 2660144320 Hz quality -100

If I disable the uhci and ehci drivers in the kernel, I can get into ddb
at that point, and "show event" shows a rapidly increasing int 19, which
is where uhci2, uhci4, piixide0 and piixide1 (or ahcisata0, if I change
the disk mode in the BIOS from IDE to RAID) attach to.

Two workarounds make the system boot completely and run stable:

- disable USB in the BIOS (but it has no ps/2 so this is rather useless)

- boot -1 (UP, this is how I have been using this machine so far)

I will append dmesg and acpidump information in follow-up.

Any ideas how to fix this, so this machine can be used with USB _and_
SMP enabled?

Thanks, 

        Geert
>How-To-Repeat:
Boot GENERIC or INSTALL kernel with default settings (USB enabled in the
BIOS, SMP enabled in the kernel/bootloader) on an Inspiron 530.
>Fix: