AIC7XXX build broken in 2.5.15+Kbuild?

[Nathan]

Using Kbuild-2.5 core 12, common against 2.5.15-1, i386 against 
2.5.15-1, and some ACPI fixups in arch/i386/{pci,kernel}/Makefile.in to 
make their latest patch work.

It doesn't build with "make -f Makefile-2.5" and trying to specify it 
manually gives:

$ make -f Makefile-2.5 drivers/scsi/aic7xxx/aic7xxx_core.o
Using ARCH='i386' AS='as' LD='ld' CC='/usr/bin/gcc' CPP='/usr/bin/gcc 
-E' AR='ar' HOSTAS='as' HOSTLD='gcc' HOSTCC='gcc' HOSTAR='ar'
Generating global Makefile
  phase 1 (find all inputs)
  phase 2 (convert all Makefile.in files)
  phase 3 (evaluate selections)
  phase 4 (integrity checks, write global makefile)
Starting phase 5 (build) for drivers/scsi/aic7xxx/aic7xxx_core.o
make[1]: Nothing to be done for `drivers/scsi/aic7xxx/aic7xxx_core.o'.
Phase 5 complete for drivers/scsi/aic7xxx/aic7xxx_core.o

Relevant configs:

CONFIG_SCSI_AIC7XXX=m
CONFIG_AIC7XXX_CMDS_PER_DEVICE=253
CONFIG_AIC7XXX_RESET_DELAY_MS=15000
# CONFIG_AIC7XXX_BUILD_FIRMWARE is not set

The build system *does* get all the sr_mod, sd_mod, etc. files.

Help!

--Nathan