Eliminate the use of commons in the kernel and modules,

simplifying the module linking process and eliminating the risks
associated with doubly-defined variables.

Cases where commons were legitimately used (detection of
compiled-in subsystems) have been converted to use sysinits, and
any new code should use this or an equivalent practice as a
matter of course.

Modules can override this behaviour by substituting -fno-common
out of ${CFLAGS} in cases where commons are necessary
(eg. third-party object modules).  Commons will be resolved and
allocated space when the kld is linked as part of the module
build process, so they will not pose a risk to the kernel or
other modules.

Provide a mechanism for controlling the export of symbols from
the module namespace.  The EXPORT_SYMS variable may be set in the
Makefile to NO (export no symbols), a list of symbols to export,
or the name of a file containing a newline-seperated list of
symbols to be exported.  Non-exported symbols are converted to
local symbols.  If EXPORT_SYMS is not set, all global symbols are
currently exported.  This behaviour is expected to change (to
exporting no symbols) once modules have been converted.

Reviewed by:	peter (in principle)
Obtained from:	green (kmod_syms.awk)

1 files changed, 2 insertions, 2 deletions

diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
index 06fdf84..0feec79 100644
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -38,7 +38,7 @@ INCLUDES+= -I/usr/include
 .endif
 
 COPTS=	${INCLUDES} ${IDENT} -D_KERNEL -ffreestanding -include opt_global.h
-CFLAGS=	${COPTFLAGS} ${CWARNFLAGS} ${DEBUG} ${COPTS}
+CFLAGS=	${COPTFLAGS} ${CWARNFLAGS} ${DEBUG} ${COPTS} -fno-common
 
 # XXX LOCORE means "don't declare C stuff" not "for locore.s".
 ASM_CFLAGS= -x assembler-with-cpp -DLOCORE ${CFLAGS}
@@ -76,7 +76,7 @@ SYSTEM_SFILES= $S/$M/$M/locore.s
 SYSTEM_DEP= Makefile ${SYSTEM_OBJS}
 SYSTEM_OBJS= locore.o vnode_if.o ${OBJS} hints.o env.o config.o hack.So
 SYSTEM_LD= @${LD} ${FMT} -Bdynamic -T $S/conf/ldscript.$M \
-	-export-dynamic -dynamic-linker /red/herring \
+	-warn-common -export-dynamic -dynamic-linker /red/herring \
 	-o ${.TARGET} -X ${SYSTEM_OBJS} vers.o
 SYSTEM_LD_TAIL= @${OBJCOPY} --strip-symbol gcc2_compiled. ${.TARGET} ; \
 	${SIZE} ${FMT} ${.TARGET} ; chmod 755 ${.TARGET}