panic amd64 !ifattr || cfdriver_get_iattr(parent->dv_cfd river, ifattr)

[David Shao <davshao%gmail.com@localhost>]

Current NetBSD 6.99.4 on amd64 Asus M5A87 motherboard AMD 870 / SB850 chipset
Many versions booted and functioned fine until sometime Friday.  Now
panic message on boot ending in:

LPTE (PNP0400) at acpi0 not configured
SIOR (PNP0C02) at acpi0 not configured
aibs0 at acip0 (ASOC, ATK0110-16843024): ASUSTeK AI Booster
UAR1 (PNP0501) at acpi0 not configured
OMSC (PNP0C02) at acpi0 not configured
RMSC (PNP0C02) at acpi0 not configured
PCIE (PNP0C02) at acpi0 not configured
RMEM (PNP0C01) at acpi0 not configured
acpibut0 at acpi0 (PWRB, PNP0C0C-170): ACPI Power Button
acpiwmi0 at acpi0 (AOD, PNP0C14-0): ACPI WMI Interface
acpiwmibus at acpiwmi0 not configured
attimer1: attached to pcppi1
pci0 at mainbus0 bus 0: configuration mode 1
pchb0 at pci0 dev 0 function 0: vendor 0x1002 product 0x5957 (rev. 0x00)
panic: kernel diagnostic assertion "!ifattr || cfdriver_get_iattr(parent->dv_cfd
river, ifattr)" failed: file "/usr/src/sys/kern/subr_autoconf.c", line 945
fatal breakpoint trap in supervisor mode
trap type 1 code 0 rip ffffffff80254af5 cs 8 rflags 246 cr2  0 cpl 8 rsp fffffff
f8108c830
Stopped in pid 0.1 (system) at  netbsd:breakpoint+0x5:  leave