Okay, my sources are up to date as of about a minute before this mailing,
and this is still happening:
<dive@eros(/sys/arch/i386/conf)> % config EROS
../../../../arch/i386/conf/files.i386:138: undefined attribute 
ainbus'
../../../../arch/i386/conf/files.i386:304: undefined attribute 
ainbus'
../../../../arch/i386/conf/files.i386:315: undefined attribute 
ainbus'
../../../../arch/i386/pnpbios/files.pnpbios:6: undefined attribute 
ainbus'
../../../../arch/i386/conf/files.i386:465: undefined attribute 
ainbus'
*** Stop.
Exit 1
<dive@eros(/sys/arch/i386/conf)> % 

Any ideas?

I haven't built a kernel since yesterday, so something since then must be
causing it. I've remade includes (in /usr/src) and rebuilt config.
my config file is:

# eros.endersgame.net kernel configuration [NetBSD 1.6O current i386]
# $egnet: EROS,v 1.148 2003/02/27 23:52:06 dive Exp $

machine 	i386

ident		"EROS"

maxusers	64

makeoptions	COPTS="-O2 -march=pentiumpro -mcpu=pentiumpro"

options		DDB
options 	I686_CPU
options 	EXEC_AOUT
options 	EXEC_ELF32
options 	EXEC_SCRIPT
options 	DUMMY_NOPS
options		KTRACE
options 	MTRR
options 	UCONSOLE
options		USERCONF
options 	RTC_OFFSET=0
options 	NTP
options 	SYSVMSG
options 	SYSVSEM
options		SYSVSHM
options		COMPAT_LINUX
options		NMBCLUSTERS=4096
options		USER_LDT
options 	QUOTA
options 	GATEWAY
options 	INET
options 	IPFILTER_LOG
options		IPFILTER_DEFAULT_BLOCK
options 	WSEMUL_VT100
options 	WS_KERNEL_FG=WSCOL_GREEN
options 	WSDISPLAY_COMPAT_PCVT
options 	WSDISPLAY_COMPAT_SYSCONS
options 	WSDISPLAY_COMPAT_USL
options 	WSDISPLAY_COMPAT_RAWKBD
options 	XSERVER
options 	PCIBIOS
options		LKM
options		USE_TOPDOWN_VM
options		LFS_UBC

file-system	FFS
file-system	CD9660
file-system	LFS

config		netbsd root on wd0a type ffs dumps on wd0b
mainbus0	at root
cpu0		at mainbus0
pci0		at mainbus0 bus 0
pchb0		at pci0 dev 0 function 0
agp0		at pchb0
ppb0		at pci0 dev 1 function 0
ppb1		at pci0 dev 11 function 0
pci1		at ppb0 bus 1
pci2		at ppb1 bus 2
pcib0		at pci0 dev 7 function 0
isa0		at pcib0
isapnp0		at isa0
npx0		at isa0 port 0xf0 irq 13
pckbc0		at isa0
pckbd0		at pckbc0
vga0		at pci1 dev 0 function 0
wsdisplay0	at vga0 console ?
wskbd0 		at pckbd0 console ? mux 1
com0		at isa0 port 0x3f8 irq 4
lpt0		at isa0 port 0x378 irq 7
fdc0		at isa0 port 0x3f0 irq 6 drq 2
pcppi0		at isa0 port 0x61
sysbeep0	at pcppi0
spkr0		at pcppi0
pciide0 	at pci0 dev 7 function 1 flags 0x0000
pciide1		at pci0 dev 13 function 0 flags 0x0000
atapibus0	at pciide0 channel 0
atapibus1	at pciide0 channel 1
wd0		at pciide1 channel 0 drive 0 flags 0x0000
wd1		at pciide1 channel 1 drive 0 flags 0x0000
cd0		at atapibus0 drive 0 flags 0x0000
cd1		at atapibus0 drive 1 flags 0x0000
cd2		at atapibus1 drive 0 flags 0x0000
fd0		at fdc0 drive 0
tl0		at pci2 dev 0 function 0
tl1		at pci2 dev 1 function 0
nsphy*		at mii? phy ?
tlphy*		at mii? phy ?
sb0		at isapnp0
audio0		at sb0
opl0		at sb0
uhci0		at pci0	dev 7 function 2
usb0		at uhci0
uhub0		at usb0
uhidev*		at uhub? port ? configuration ? interface ?
ums*		at uhidev? reportid ?
wsmouse*	at ums? mux 0

pseudo-device	vnd		2
pseudo-device	bpfilter	8
pseudo-device	ipfilter
pseudo-device	loop
pseudo-device	pty
pseudo-device	rnd
pseudo-device	wsmux
pseudo-device	wsfont
pseudo-device	clockctl

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