dmesg

...
viaide0 at pci0 dev 7 function 0
viaide0: NVIDIA nForce4 Serial ATA Controller (rev. 0xf3)
viaide0: using ioapic0 pin 11 for native-PCI interrupt
atabus0 at viaide0 channel 0
atabus1 at viaide0 channel 1
viaide1 at pci0 dev 8 function 0
viaide1: NVIDIA nForce4 Serial ATA Controller (rev. 0xf3)
pci_intr_map: bus 0 dev 8 func 0 pin 1; line 10
pci_intr_map: no MP mapping found

Hung after above message is shown.
amd64 6.99.19

viaide0 at pci0 dev 7 function 0: NVIDIA nForce4 Serial ATA Controller (rev. 0xf3)
viaide0: bus-master DMA support present
viaide0: primary channel wired to native-PCI mode
LTID: Picked IRQ 22 with weight 0
viaide0: using ioapic0 pin 22 for native-PCI interrupt
atabus0 at viaide0 channel 0
viaide0: secondary channel wired to native-PCI mode
atabus1 at viaide0 channel 1
viaide1 at pci0 dev 8 function 0: NVIDIA nForce4 Serial ATA Controller (rev. 0xf3)
viaide1: bus-master DMA support present
viaide1: primary channel wired to native-PCI mode
LSI1: Picked IRQ 23 with weight 0
viaide1: using ioapic0 pin 23 for native-PCI interrupt
atabus2 at viaide1 channel 0
viaide1: secondary channel wired to native-PCI mode
atabus3 at viaide1 channel 1

Having panic(" .."); after the line, and bt in ddb, the calling sequence to pci_intr_map is as follows.

main -> 
cpu_configure -> 
config_rootfound -> 
config_attach -> 
config_attach_loc -> 
mainbus_attach -> 
config_found_ia -> 
config_attach_loc -> 
pciattach -> 
pcirescan -> 
pci_enumerate_bus -> 
pci_probe_device -> 
config_attach_loc -> 
viaide_attach ->
pciide_common_attach -> 
via_sata_chip_map ->
pciide_mapchan -> 
pciide_mapregs_native -> 
pci_intr_map

current-users (2010/08/03) says,

Disabling ACPI and SMP "boot netbsd -12" can boot my system.

current-users (2010/09/08)
YES, 'boot netbsd -12' boots fine