kernel--make error - BBS

cd /sys/i386/conf/
cp GENERIC MYKERNEL
ee MYKERNEL
config MYKERMEL
cd ../../compile/MYKERNEL
make depend
make <-----------------執行到這邊出現以下 error
請問這樣的話要如何解決

root [/sys/compile/MYKERNEL] # make
linking kernel
ffs_softdep.o: In function `softdep_flushfiles':
ffs_softdep.o(.text+0x803): undefined reference to `ffs_flushfiles'
ffs_softdep.o(.text+0x8ea): undefined reference to `ffs_flushfiles'
ffs_softdep.o: In function `handle_workitem_freefrag':
ffs_softdep.o(.text+0x14bd): undefined reference to `ffs_blkfree'
ffs_softdep.o: In function `handle_workitem_freeblocks':
ffs_softdep.o(.text+0x21d0): undefined reference to `ffs_blkfree'
ffs_softdep.o(.text+0x2246): undefined reference to `ffs_blkfree'
ffs_softdep.o: In function `indir_trunc':
ffs_softdep.o(.text+0x2403): undefined reference to `ffs_blkfree'
ffs_softdep.o: In function `handle_workitem_freefile':
ffs_softdep.o(.text+0x314c): undefined reference to `ffs_freefile'
kbd.o: In function `kbd_register':
kbd.o(.text+0x30a): undefined reference to `kbddriver_set'
kbd.o(.text+0x311): undefined reference to `kbddriver_set'
kbd.o: In function `kbd_get_switch':
kbd.o(.text+0x418): undefined reference to `kbddriver_set'
kbd.o(.text+0x41d): undefined reference to `kbddriver_set'
kbd.o: In function `kbd_configure':
kbd.o(.text+0x697): undefined reference to `kbddriver_set'
kbd.o(.text+0x69c): more undefined references to `kbddriver_set' follow
*** Error code 1

Stop in /usr/src/sys/compile/MYKERNEL.
root [/sys/compile/MYKERNEL] #

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