Allow the kernel to build with a compiler that sets -fno-common.

The mechanism that generates assym.inc and offset.inc depends on the
symbols in question being common. For now, simply force the object files
to be created with -fcommon.

-fno-common will be the default in GCC10/LLVM11.

Submitted by:	arichardson
Reviewed by:	kevans
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D24322

1 files changed, 3 insertions, 3 deletions

diff --git a/sys/conf/kern.post.mk b/sys/conf/kern.post.mk
index e5aeac68d8fa..529a02ac6796 100644
--- a/sys/conf/kern.post.mk
+++ b/sys/conf/kern.post.mk
@@ -235,20 +235,20 @@ offset.inc: $S/kern/genoffset.sh genoffset.o
 	NM='${NM}' NMFLAGS='${NMFLAGS}' sh $S/kern/genoffset.sh genoffset.o > ${.TARGET}
 
 genoffset.o: $S/kern/genoffset.c
-	${CC} -c ${CFLAGS:N-flto:N-fno-common} $S/kern/genoffset.c
+	${CC} -c ${CFLAGS:N-flto:N-fno-common} -fcommon $S/kern/genoffset.c
 
 # genoffset_test.o is not actually used for anything - the point of compiling it
 # is to exercise the CTASSERT that checks that the offsets in the offset.inc
 # _lite struct(s) match those in the original(s). 
 genoffset_test.o: $S/kern/genoffset.c offset.inc
-	${CC} -c ${CFLAGS:N-flto:N-fno-common} -DOFFSET_TEST \
+	${CC} -c ${CFLAGS:N-flto:N-fno-common} -fcommon -DOFFSET_TEST \
 	    $S/kern/genoffset.c -o ${.TARGET}
 
 assym.inc: $S/kern/genassym.sh genassym.o genoffset_test.o
 	NM='${NM}' NMFLAGS='${NMFLAGS}' sh $S/kern/genassym.sh genassym.o > ${.TARGET}
 
 genassym.o: $S/$M/$M/genassym.c  offset.inc
-	${CC} -c ${CFLAGS:N-flto:N-fno-common} $S/$M/$M/genassym.c
+	${CC} -c ${CFLAGS:N-flto:N-fno-common} -fcommon $S/$M/$M/genassym.c
 
 OBJS_DEPEND_GUESS+= opt_global.h
 genoffset.o genassym.o vers.o: opt_global.h