Rather than preparing the efi source file, we will make the symbolic
link as needed from the build location.

The `ln` command is run every time to allow to update the link in case
the source tree change location.

This patch also introduce "efi-common.mk" which allow to reuse the
common make instructions without having to duplicate them into each
arch.

And now that we have a list of common source file, we can start to
remove the links to the source files on clean.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---

Notes:
    v10:
    - acked
    - small change to comment in efi_common.mk
    - rebased, removed change "subdir- += efi" in xen/arch/x86/Makefile as
      it isn't needed anymore.
    
    v9:
    - rename efi_common.mk to efi-common.mk
    - generalize comment about cleaning "efi" and "boot" subdir in x86.
    - add a space after the other comma of $(patsubst )
    - create a relative symlink instead of an absolute one
    - with the above, we don't need to use $(abs_srctree) anymore in the
      prerequisite of the link to the efi source file, use $(srctree).
    
    v8:
    - use symbolic link instead of making a copy of the source
    - introduce efi_common.mk
    - remove links to source file on clean
    - use -iquote for "efi.h" headers in common/efi

 xen/Makefile                 |  5 -----
 xen/arch/arm/efi/Makefile    |  4 ++--
 xen/arch/x86/efi/Makefile    |  5 +----
 xen/common/efi/efi-common.mk | 15 +++++++++++++++
 4 files changed, 18 insertions(+), 11 deletions(-)
 create mode 100644 xen/common/efi/efi-common.mk

diff --git a/xen/Makefile b/xen/Makefile
index 18a4f7e1015a..dec489f2a909 100644
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -441,11 +441,6 @@ $(TARGET).gz: $(TARGET)
 $(TARGET): FORCE
 	$(Q)$(MAKE) $(build)=tools
 	$(Q)$(MAKE) $(build)=. include/xen/compile.h
-	[ -e arch/$(TARGET_ARCH)/efi ] && for f in $$(cd common/efi; echo *.[ch]); \
-		do test -r arch/$(TARGET_ARCH)/efi/$$f || \
-		   ln -nsf ../../../common/efi/$$f arch/$(TARGET_ARCH)/efi/; \
-		done; \
-		true
 	$(Q)$(MAKE) $(build)=include all
 	$(Q)$(MAKE) $(build)=arch/$(TARGET_ARCH) include
 	$(Q)$(MAKE) $(build)=. arch/$(TARGET_ARCH)/include/asm/asm-offsets.h
diff --git a/xen/arch/arm/efi/Makefile b/xen/arch/arm/efi/Makefile
index 1b1ed06feddc..4313c390665f 100644
--- a/xen/arch/arm/efi/Makefile
+++ b/xen/arch/arm/efi/Makefile
@@ -1,4 +1,4 @@
-CFLAGS-y += -fshort-wchar
+include $(srctree)/common/efi/efi-common.mk
 
-obj-y += boot.init.o pe.init.o ebmalloc.o runtime.o
+obj-y += $(EFIOBJ-y)
 obj-$(CONFIG_ACPI) +=  efi-dom0.init.o
diff --git a/xen/arch/x86/efi/Makefile b/xen/arch/x86/efi/Makefile
index e08b4d8e4808..034ec87895df 100644
--- a/xen/arch/x86/efi/Makefile
+++ b/xen/arch/x86/efi/Makefile
@@ -1,4 +1,4 @@
-CFLAGS-y += -fshort-wchar
+include $(srctree)/common/efi/efi-common.mk
 
 quiet_cmd_objcopy_o_ihex = OBJCOPY $@
 cmd_objcopy_o_ihex = $(OBJCOPY) -I ihex -O binary $< $@
@@ -8,9 +8,6 @@ $(obj)/%.o: $(src)/%.ihex FORCE
 
 $(obj)/boot.init.o: $(obj)/buildid.o
 
-EFIOBJ-y := boot.init.o pe.init.o ebmalloc.o runtime.o
-EFIOBJ-$(CONFIG_COMPAT) += compat.o
-
 $(call cc-option-add,cflags-stack-boundary,CC,-mpreferred-stack-boundary=4)
 $(addprefix $(obj)/,$(EFIOBJ-y)): CFLAGS_stack_boundary := $(cflags-stack-boundary)
 
diff --git a/xen/common/efi/efi-common.mk b/xen/common/efi/efi-common.mk
new file mode 100644
index 000000000000..960d44a6d55b
--- /dev/null
+++ b/xen/common/efi/efi-common.mk
@@ -0,0 +1,15 @@
+EFIOBJ-y := boot.init.o pe.init.o ebmalloc.o runtime.o
+EFIOBJ-$(CONFIG_COMPAT) += compat.o
+
+CFLAGS-y += -fshort-wchar
+CFLAGS-y += -iquote $(srctree)/common/efi
+
+# Part of the command line transforms $(obj)
+# e.g.: It transforms "dir/foo/bar" into successively
+#       "dir foo bar", ".. .. ..", "../../.."
+$(obj)/%.c: $(srctree)/common/efi/%.c FORCE
+	$(Q)ln -nfs $(subst $(space),/,$(patsubst %,..,$(subst /, ,$(obj))))/common/efi/$(<F) $@
+
+clean-files += $(patsubst %.o, %.c, $(EFIOBJ-y:.init.o=.o) $(EFIOBJ-))
+
+.PRECIOUS: $(obj)/%.c
-- 
Anthony PERARD

Hi Anthony,

On 22/03/2022 11:22, Anthony PERARD wrote:
> Rather than preparing the efi source file, we will make the symbolic
> link as needed from the build location.
> 
> The `ln` command is run every time to allow to update the link in case
> the source tree change location.
> 
> This patch also introduce "efi-common.mk" which allow to reuse the
> common make instructions without having to duplicate them into each
> arch.
> 
> And now that we have a list of common source file, we can start to
> remove the links to the source files on clean.
> 
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> Acked-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Julien Grall <jgrall@amazon.com>

Cheers,

-- 
Julien Grall

Hi Julien, Stefano, Bertrand,

Could I get a ack on this patch and the next one
"[XEN PATCH v10 2/7] build: replace $(BASEDIR) by $(objtree)" for the
Arm part?

Cheers,

On Tue, Mar 22, 2022 at 11:22:32AM +0000, Anthony PERARD wrote:
> Rather than preparing the efi source file, we will make the symbolic
> link as needed from the build location.
> 
> The `ln` command is run every time to allow to update the link in case
> the source tree change location.
> 
> This patch also introduce "efi-common.mk" which allow to reuse the
> common make instructions without having to duplicate them into each
> arch.
> 
> And now that we have a list of common source file, we can start to
> remove the links to the source files on clean.
> 
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> Acked-by: Jan Beulich <jbeulich@suse.com>

-- 
Anthony PERARD