kbuild: asm symlink support for arch/$ARCH/include

Adjust the asm symlink support so we do not create the
symlink unless really needed.
We check the precense of include/asm-$ARCH by checking
for the system.h file. We may end up with a stale directory
so it is not enough to check if the directory is present.

Signed-off-by: Sam Ravnborg <[email protected]>

Kbuild

@@ -43,7 +43,7 @@ $(obj)/$(bounds-file): kernel/bounds.s Kbuild
 # 2) Generate asm-offsets.h
 #
 
-offsets-file := include/asm-$(SRCARCH)/asm-offsets.h
+offsets-file := include/asm/asm-offsets.h
 
 always += $(offsets-file)
 targets += $(offsets-file)
@@ -81,7 +81,6 @@ arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
  $(call if_changed_dep,cc_s_c)
 
 $(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
- $(Q)mkdir -p $(dir $@)
  $(call cmd,offsets)
 
 #####

Makefile

@@ -925,7 +925,9 @@ ifneq ($(KBUILD_SRC),)
  /bin/false; \
  fi;
  $(Q)if [ ! -d include2 ]; then mkdir -p include2; fi;
- $(Q)ln -fsn $(srctree)/include/asm-$(SRCARCH) include2/asm
+ $(Q)if [ -e $(srctree)/include/asm-$(SRCARCH)/system.h ]; then \
+ ln -fsn $(srctree)/include/asm-$(SRCARCH) include2/asm; \
+ fi
 endif
 
 # prepare2 creates a makefile if using a separate output directory
@@ -951,22 +953,34 @@ export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH)
 
 # The asm symlink changes when $(ARCH) changes.
 # Detect this and ask user to run make mrproper
-
-include/asm: FORCE
- $(Q)set -e; asmlink=`readlink include/asm | cut -d '-' -f 2`; \
- if [ -L include/asm ]; then  \
- if [ "$$asmlink" != "$(SRCARCH)" ]; then \
+define check-symlink
+ set -e; \
+ if [ -L include/asm ]; then  \
+  asmlink=`readlink include/asm | cut -d '-' -f 2`; \
+ if [ "$$asmlink" != "$(SRCARCH)" ]; then  \
  echo "ERROR: the symlink $@ points to asm-$$asmlink but asm-$(SRCARCH) was expected"; \
  echo " set ARCH or save .config and run 'make mrproper' to fix it"; \
- exit 1; \
- fi; \
- else \
- echo ' SYMLINK $@ -> include/asm-$(SRCARCH)'; \
- if [ ! -d include ]; then \
- mkdir -p include; \
- fi; \
- ln -fsn asm-$(SRCARCH) $@; \
+ exit 1; \
+ fi; \
+ fi
+endef
+
+# We create the target directory of the symlink if it does
+# not exist so the test in chack-symlink works and we have a
+# directory for generated filesas used by some architectures.
+define create-symlink
+ if [ ! -L include/asm ]; then \
+ echo ' SYMLINK $@ -> include/asm-$(SRCARCH)'; \
+ if [ ! -d include/asm-$(SRCARCH) ]; then \
+ mkdir -p include/asm-$(SRCARCH); \
+ fi; \
+ ln -fsn asm-$(SRCARCH) $@; \
  fi
+endef
+
+include/asm: FORCE
+ $(Q)$(check-symlink)
+ $(Q)$(create-symlink)
 
 # Generate some files
 # ---------------------------------------------------------------------------