build system: Split linking into multiple steps

After collecting dependencies for ramstage, add an intermediate step
in which object files are linked per directory. The results are then
linked into the final binary.

This reduces the maximum command line length and might also help with
future use of LTO linking.

Also adapt the lint test for build dir handling, since printall
doesn't provide individual object files for ramstage anymore.

Change-Id: Ie40febd8c1eaf4609944eedeab46d870639e53df
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/1911
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

2 files changed, 38 insertions, 4 deletions

diff --git a/Makefile.inc b/Makefile.inc
index 5b62dd3ff3..7caf359844 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -60,6 +60,40 @@ subdirs-y += site-local
 # Add source classes and their build options
 classes-y := ramstage romstage smm cpu_microcode
 
+#######################################################################
+# Helper functions for ramstage postprocess
+spc :=
+spc +=
+$(spc) :=
+$(spc) +=
+
+# files-in-dir-recursive,dir,files
+files-in-dir-recursive=$(filter $(1)%,$(2))
+
+# parent-dir,dir/
+parent-dir=$(dir $(subst $( ),/,$(strip $(subst /, ,$(1)))))
+
+# filters out exactly the directory specified
+# filter-out-dir,dir_to_keep,dirs
+filter-out-dir=$(filter-out $(1),$(2))
+
+# filters out dir_to_keep and all its parents
+# filter-out-dirs,dir_to_keep,dirs
+filter-out-dirs=$(if $(filter-out ./,$(1)),$(call filter-out-dirs,$(call parent-dir,$(1)),$(call filter-out-dir,$(1),$(2))),$(call filter-out-dir,$(1),$(2)))
+
+# dir-wildcards,dirs
+dir-wildcards=$(addsuffix %,$(1))
+
+# files-in-dir,dir,files
+files-in-dir=$(filter-out $(call dir-wildcards,$(call filter-out-dirs,$(1),$(dir $(2)))),$(call files-in-dir-recursive,$(1),$(2)))
+
+#######################################################################
+# reduce command line length by linking the objects of each
+# directory into an intermediate file
+ramstage-postprocess=$(foreach d,$(sort $(dir $(1))), \
+	$(eval $(d)ramstage.o: $(call files-in-dir,$(d),$(1)); $$(LD) -o $$@ -r $$^ ) \
+	$(eval ramstage-objs:=$(d)ramstage.o $(filter-out $(call files-in-dir,$(d),$(1)),$(ramstage-objs))))
+
 romstage-c-ccopts:=-D__PRE_RAM__
 romstage-S-ccopts:=-D__PRE_RAM__
 ifeq ($(CONFIG_TRACE),y)
diff --git a/util/lint/lint-stable-002-build-dir-handling b/util/lint/lint-stable-002-build-dir-handling
index ca61a351f0..2dad8a6e47 100755
--- a/util/lint/lint-stable-002-build-dir-handling
+++ b/util/lint/lint-stable-002-build-dir-handling
@@ -61,10 +61,10 @@ $MAKE DOTCONFIG=$TMPCONFIG allyesconfig >/dev/null
 CURRENTDIR=`pwd -P`
 PARENTDIR=`dirname $CURRENTDIR`
 
-compare_output "`run_printall build`" "build/.../static.c build/.../static.c build/.../static.ramstage.o build/.../static.romstage.o"
-compare_output "`run_printall ../obj`" "$PARENTDIR/obj/.../static.c $PARENTDIR/obj/.../static.c $PARENTDIR/obj/.../static.ramstage.o $PARENTDIR/obj/.../static.romstage.o"
-compare_output "`run_printall /tmp`" "/tmp/.../static.c /tmp/.../static.c /tmp/.../static.ramstage.o /tmp/.../static.romstage.o"
-compare_output "`run_printall /../tmp`" "/tmp/.../static.c /tmp/.../static.c /tmp/.../static.ramstage.o /tmp/.../static.romstage.o"
+compare_output "`run_printall build`" "build/.../static.c build/.../static.c build/.../static.romstage.o"
+compare_output "`run_printall ../obj`" "$PARENTDIR/obj/.../static.c $PARENTDIR/obj/.../static.c $PARENTDIR/obj/.../static.romstage.o"
+compare_output "`run_printall /tmp`" "/tmp/.../static.c /tmp/.../static.c /tmp/.../static.romstage.o"
+compare_output "`run_printall /../tmp`" "/tmp/.../static.c /tmp/.../static.c /tmp/.../static.romstage.o"
 
 rm -f $TMPCONFIG