Hej!
I just tried to build a kernel with COMPAT_LINUX on, but it failed 
miserably in the link stage:
cc  -O6 -I. -I../../../../arch -I../../../.. -I../../../../sys -DI486_CPU -DI586_CPU -DMATH_EMULATE -DDUMMY_NOPS -DXSERVER -DUCONSOLE -DMACHINE_NONCONTIG -DPCVT_INHIBIT_NUMLOCK -DTIMEZONE="0xffffffc4" -DDST="1" -DSWAPPAGER -DVNODEPAGER -DDEVPAGER -DDIAGNOSTIC -DKTRACE -DSYSVMSG -DSYSVSEM -DSYSVSHM -DCOMPAT_NOMID -DCOMPAT_LINUX -DCOMPAT_10 -DCOMPAT_43 -DTCP_COMPAT_42 -DCOMPAT_SVR4 -DLKM -DFFS -DMFS -DNFSCLIENT -DNFSSERVER -DCD9660 -DMSDOSFS -DFDESC -DFIFO -DKERNFS -DPROCFS -DUNION -DGATEWAY -DINET -DISO -DTPIP -DCCITT -DLLC -DHDLC -DKERNEL -Di386 -c vers.c
rm -f netbsd
ld -x -z -T F8100000 -o netbsd -e start ${SYSTEM_OBJ} vers.o
linux_sysent.o: Undefined symbol `_compat_09_setdomainname' referenced from data segment
*** Error code 1

So, obviously it seems like you have to specify COMPAT_09 in order to get 
COMPAT_LINUX to work.  Looks like a bug to me.  If you insist, I send-pr it.

Gruesse
	Oskar

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 					Tragbar ist, was nicht herunterfaellt.
						    oskar@zappa.unna.ping.de
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