Re: MI linker script

[Masao Uebayashi <uebayasi%gmail.com@localhost>]

For reference, this *actually* works, and intermediate *.ro is rm'ed.  (This
needs the uncommitted __SYMVAL() change in sys/cdefs_elf.h.)

I'm not committing this soon, to give people time to overcome fear against
ld -r.

Index: sys/conf/Makefile.kern.inc
===================================================================
RCS file: /cvsroot/src/sys/conf/Makefile.kern.inc,v
retrieving revision 1.178
diff -p -u -r1.178 Makefile.kern.inc
--- sys/conf/Makefile.kern.inc	6 Nov 2014 12:02:59 -0000	1.178
+++ sys/conf/Makefile.kern.inc	8 Nov 2014 04:32:56 -0000
@@ -223,8 +223,9 @@ ${_cfile:T:R}.o: ${_cfile}
 # load lines for config "xxx" will be emitted as:
 # xxx: ${SYSTEM_DEP} swapxxxx.o vers.o build_kernel
 
+MI_LDSCRIPT=	$S/conf/kern.ldscript
 SYSTEM_OBJ?=	${MD_OBJS} ${MI_OBJS} ${OBJS:O} ${SYSLIBCOMPAT} ${LIBKERN}
-SYSTEM_DEP+=	Makefile ${SYSTEM_OBJ:O} .gdbinit
+SYSTEM_DEP+=	Makefile ${SYSTEM_OBJ:O} .gdbinit ${MI_LDSCRIPT}
 .if defined(KERNLDSCRIPT)
 SYSTEM_DEP+=	${KERNLDSCRIPT}
 .endif
@@ -234,10 +235,16 @@ SYSTEM_CTFMERGE= ${CTFMERGE} ${CTFMFLAGS
 SYSTEM_CTFMERGE= ${_MKSHECHO}
 .endif
 SYSTEM_LD_HEAD?=@rm -f $@
+SYSTEM_LD_RO?=	@${_MKSHMSG} "   link  ${.CURDIR:T}/${.TARGET}.ro"; \
+		${_MKSHECHO}\
+		${LD} -r -T ${MI_LDSCRIPT} -Map $@.ro.map -o $@.ro\
+		    '$${SYSTEM_OBJ}' '$${EXTRA_OBJ}' vers.o; \
+		${LD} -r -T ${MI_LDSCRIPT} -Map $@.ro.map -o $@.ro\
+		    ${SYSTEM_OBJ} ${EXTRA_OBJ} vers.o
 SYSTEM_LD?=	@${_MKSHMSG} "   link  ${.CURDIR:T}/${.TARGET}"; \
 		${_MKSHECHO}\
-		${LD} -Map $@.map --cref ${LINKFLAGS} -o $@ '$${SYSTEM_OBJ}' '$${EXTRA_OBJ}' vers.o; \
-		${LD} -Map $@.map --cref ${LINKFLAGS} -o $@ ${SYSTEM_OBJ} ${EXTRA_OBJ} vers.o
+		${LD} -Map $@.map --cref ${LINKFLAGS} -o $@ $@.ro; \
+		${LD} -Map $@.map --cref ${LINKFLAGS} -o $@ $@.ro
 
 TEXTADDR?=	${LOADADDRESS}			# backwards compatibility
 LINKTEXT?=	${TEXTADDR:C/.+/-Ttext &/}
@@ -346,7 +353,7 @@ assym.h machdep.o: Makefile
 .if !target(__CLEANKERNEL)
 __CLEANKERNEL: .USE
 	${_MKMSG} "${.TARGET}ing the kernel objects"
-	rm -f ${KERNELS} *.map eddep tags *.[io] *.ko *.ln [a-z]*.s vers.c \
+	rm -f ${KERNELS} *.map eddep tags *.[io] *.ro *.ko *.ln [a-z]*.s vers.c \
 	    [Ee]rrs linterrs makelinks assym.h.tmp assym.h \
 	    ${EXTRA_KERNELS} ${EXTRA_CLEAN}
 .endif
@@ -553,21 +560,26 @@ CPPFLAGS.kern_ksyms_buf.c+=	-DCOPY_SYMTA
 .if !defined(COPY_SYMTAB)
 build_kernel: .USE
 	${SYSTEM_LD_HEAD}
-	${SYSTEM_LD} swap${.TARGET}.o
+	${SYSTEM_LD_RO} swap${.TARGET}.o
+	${SYSTEM_LD}
 	${SYSTEM_LD_TAIL_STAGE2}
+	@rm -f ${.TARGET}.ro
 .else
 build_kernel: .USE
 	${CC} ${CFLAGS} ${CPPFLAGS} -DCOPY_SYMTAB \
 	    -c $S/kern/kern_ksyms_buf.c -o kern_ksyms_buf.o
 	${SYSTEM_LD_HEAD}
-	${SYSTEM_LD} swap${.TARGET}.o kern_ksyms_buf.o
+	${SYSTEM_LD_RO} swap${.TARGET}.o kern_ksyms_buf.o
+	${SYSTEM_LD}
 	${SYSTEM_LD_TAIL_STAGE1}
 	${CC} ${CFLAGS} ${CPPFLAGS} -DCOPY_SYMTAB \
 	    -DSYMTAB_SPACE=$$(${DBSYM} -P ${.TARGET}${TARGETSFX}) \
 	    -c $S/kern/kern_ksyms_buf.c -o kern_ksyms_buf_real.o
 	${SYSTEM_LD_HEAD}
-	${SYSTEM_LD} swap${.TARGET}.o kern_ksyms_buf_real.o
+	${SYSTEM_LD_RO} swap${.TARGET}.o kern_ksyms_buf_real.o
+	${SYSTEM_LD}
 	${SYSTEM_LD_TAIL_STAGE2}
+	@rm -f ${.TARGET}.ro
 .endif
 
 .include <bsd.files.mk>
Index: sys/conf/kern.ldscript
===================================================================
RCS file: sys/conf/kern.ldscript
diff -N sys/conf/kern.ldscript
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ sys/conf/kern.ldscript	8 Nov 2014 04:32:56 -0000
@@ -0,0 +1,20 @@
+/*	$NetBSD$	*/
+
+SECTIONS
+{
+  .data :
+  {
+    *(.data)
+  }
+  . = ALIGN(COHERENCY_UNIT);
+  .data.cacheline_aligned :
+  {
+    *(.data.cacheline_aligned)
+  }
+  . = ALIGN(COHERENCY_UNIT);
+  .data.read_mostly :
+  {
+    *(.data.read_mostly)
+  }
+  . = ALIGN(COHERENCY_UNIT);
+}
Index: sys/conf/param.c
===================================================================
RCS file: /cvsroot/src/sys/conf/param.c,v
retrieving revision 1.64
diff -p -u -r1.64 param.c
--- sys/conf/param.c	9 Jun 2012 02:31:14 -0000	1.64
+++ sys/conf/param.c	8 Nov 2014 04:32:57 -0000
@@ -219,3 +219,8 @@ const	int mclbytes = MCLBYTES;
  * Values in support of POSIX semaphores.
  */
 int	ksem_max = KSEM_MAX;
+
+/*
+ * Symbols for linker script.
+ */
+__SYMVAL(COHERENCY_UNIT, COHERENCY_UNIT);