1. Patchew
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  3. [XEN PATCH v8 00/47] xen: Build system improvements, now with out-of-tree build!
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[XEN PATCH v8 07/47] build: set ALL_OBJS to main Makefile; move prelink.o to main Makefile

Anthony PERARD posted 47 patches 3 years ago
There is a newer version of this series
[XEN PATCH v8 07/47] build: set ALL_OBJS to main Makefile; move prelink.o to main Makefile
Posted by Anthony PERARD 3 years ago 
This is to avoid arch/$arch/Makefile having to recurse into parents
directories.

This avoid duplication of the logic to build prelink.o between arches.

In order to do that, we cut the $(TARGET) target in the main Makefile in
two, there is a "prepare" phase/target runned before starting to build
"prelink.o" which will prepare "include/" among other things, then all
the $(ALL_OBJS) will be generated in order to build "prelink.o" and
finally $(TARGET) will be generated by calling into "arch/*/" to make
$(TARGET).

Now we don't need to prefix $(ALL_OBJS) with $(BASEDIR) as it is now
only used from the main Makefile. Other changes is to use "$<" instead
of spelling "prelink.o" in the target "$(TARGET)" in both
arch/*/Makefile.

Beside "prelink.o" been at a different location, no other functional
change intended.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---

Notes:
    v8:
    - rebased
    - move Arm specific dependencies between $(ALL_OBJS) objects (head.o)
      into Arm specific "Rules.mk" instead of the common "build.mk".
    
    v7:
    - change, now things are in build.mk: no more prepare phase needed

 xen/Makefile          | 15 ++++++++++++++-
 xen/Rules.mk          | 13 -------------
 xen/arch/arm/Makefile | 31 ++++---------------------------
 xen/arch/arm/Rules.mk |  5 +++++
 xen/arch/arm/arch.mk  |  2 ++
 xen/arch/x86/Makefile | 29 ++++++-----------------------
 xen/arch/x86/arch.mk  |  2 ++
 xen/build.mk          | 18 ++++++++++++++++++
 8 files changed, 51 insertions(+), 64 deletions(-)

diff --git a/xen/Makefile b/xen/Makefile
index ed61f38dd335..7bb3595d649f 100644
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -285,8 +285,21 @@ CFLAGS += -flto
 LDFLAGS-$(CONFIG_CC_IS_CLANG) += -plugin LLVMgold.so
 endif
 
+# Note that link order matters!
+ALL_OBJS-y                := common/built_in.o
+ALL_OBJS-y                += drivers/built_in.o
+ALL_OBJS-y                += lib/built_in.o
+ALL_OBJS-y                += xsm/built_in.o
+ALL_OBJS-y                += arch/$(TARGET_ARCH)/built_in.o
+ALL_OBJS-$(CONFIG_CRYPTO) += crypto/built_in.o
+
+ALL_LIBS-y                := lib/lib.a
+
 include $(BASEDIR)/arch/$(TARGET_ARCH)/arch.mk
 
+export ALL_OBJS := $(ALL_OBJS-y)
+export ALL_LIBS := $(ALL_LIBS-y)
+
 # define new variables to avoid the ones defined in Config.mk
 export XEN_CFLAGS := $(CFLAGS)
 export XEN_AFLAGS := $(AFLAGS)
@@ -407,7 +420,7 @@ $(TARGET): FORCE
 	$(MAKE) -f $(BASEDIR)/Rules.mk -C include
 	$(MAKE) -f $(BASEDIR)/Rules.mk -C arch/$(TARGET_ARCH) include
 	$(MAKE) -f $(BASEDIR)/Rules.mk arch/$(TARGET_ARCH)/include/asm/asm-offsets.h
-	$(MAKE) -f $(BASEDIR)/Rules.mk -C arch/$(TARGET_ARCH) $@
+	$(MAKE) -f $(BASEDIR)/Rules.mk $@
 
 SUBDIRS = xsm arch/$(TARGET_ARCH) common drivers lib test
 define all_sources
diff --git a/xen/Rules.mk b/xen/Rules.mk
index 7b8b9047cfd5..77d359bedaf8 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -8,25 +8,12 @@
 include $(XEN_ROOT)/Config.mk
 include $(BASEDIR)/scripts/Kbuild.include
 
-# Note that link order matters!
-ALL_OBJS-y               += $(BASEDIR)/common/built_in.o
-ALL_OBJS-y               += $(BASEDIR)/drivers/built_in.o
-ALL_OBJS-y               += $(BASEDIR)/lib/built_in.o
-ALL_OBJS-y               += $(BASEDIR)/xsm/built_in.o
-ALL_OBJS-y               += $(BASEDIR)/arch/$(TARGET_ARCH)/built_in.o
-ALL_OBJS-$(CONFIG_CRYPTO)   += $(BASEDIR)/crypto/built_in.o
-
-ALL_LIBS-y               := $(BASEDIR)/lib/lib.a
-
 # Initialise some variables
 lib-y :=
 targets :=
 CFLAGS-y :=
 AFLAGS-y :=
 
-ALL_OBJS := $(ALL_OBJS-y)
-ALL_LIBS := $(ALL_LIBS-y)
-
 SPECIAL_DATA_SECTIONS := rodata $(foreach a,1 2 4 8 16, \
                                             $(foreach w,1 2 4, \
                                                         rodata.str$(w).$(a)) \
diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index d0dee10102b6..14952275772b 100644
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -75,14 +75,6 @@ ifneq ($(CONFIG_DTB_FILE),"")
 obj-y += dtb.o
 endif
 
-ALL_OBJS := $(TARGET_SUBARCH)/head.o $(ALL_OBJS)
-
-# head.o is built by descending into the sub-directory, depends on the part of
-# $(ALL_OBJS) that will eventually recurse into $(TARGET_SUBARCH)/ and build
-# head.o
-$(TARGET_SUBARCH)/head.o: $(BASEDIR)/arch/arm/built_in.o
-$(TARGET_SUBARCH)/head.o: ;
-
 ifdef CONFIG_LIVEPATCH
 all_symbols = --all-symbols
 ifdef CONFIG_FAST_SYMBOL_LOOKUP
@@ -98,33 +90,18 @@ ifeq ($(CONFIG_ARM_64),y)
 	ln -sf $(@F) $@.efi
 endif
 
-ifeq ($(CONFIG_LTO),y)
-# Gather all LTO objects together
-prelink_lto.o: $(ALL_OBJS) $(ALL_LIBS)
-	$(LD_LTO) -r -o $@ $(filter-out %.a,$^) --start-group $(filter %.a,$^) --end-group
-
-# Link it with all the binary objects
-prelink.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) prelink_lto.o
-	$(call if_changed,ld)
-else
-prelink.o: $(ALL_OBJS) $(ALL_LIBS) FORCE
-	$(call if_changed,ld)
-endif
-
-targets += prelink.o
-
-$(TARGET)-syms: prelink.o xen.lds
-	$(LD) $(XEN_LDFLAGS) -T xen.lds -N prelink.o \
+$(TARGET)-syms: $(BASEDIR)/prelink.o xen.lds
+	$(LD) $(XEN_LDFLAGS) -T xen.lds -N $< \
 	    $(BASEDIR)/common/symbols-dummy.o -o $(@D)/.$(@F).0
 	$(NM) -pa --format=sysv $(@D)/.$(@F).0 \
 		| $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort >$(@D)/.$(@F).0.S
 	$(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).0.o
-	$(LD) $(XEN_LDFLAGS) -T xen.lds -N prelink.o \
+	$(LD) $(XEN_LDFLAGS) -T xen.lds -N $< \
 	    $(@D)/.$(@F).0.o -o $(@D)/.$(@F).1
 	$(NM) -pa --format=sysv $(@D)/.$(@F).1 \
 		| $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort >$(@D)/.$(@F).1.S
 	$(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).1.o
-	$(LD) $(XEN_LDFLAGS) -T xen.lds -N prelink.o $(build_id_linker) \
+	$(LD) $(XEN_LDFLAGS) -T xen.lds -N $< $(build_id_linker) \
 	    $(@D)/.$(@F).1.o -o $@
 	$(NM) -pa --format=sysv $(@D)/$(@F) \
 		| $(BASEDIR)/tools/symbols --all-symbols --xensyms --sysv --sort \
diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
index e69de29bb2d1..290609487605 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -0,0 +1,5 @@
+# head.o is built by descending into arch/arm/$(TARGET_SUBARCH), depends on the
+# part of $(ALL_OBJS) that will eventually recurse into $(TARGET_SUBARCH)/ and
+# build head.o
+arch/arm/$(TARGET_SUBARCH)/head.o: arch/arm/built_in.o
+arch/arm/$(TARGET_SUBARCH)/head.o: ;
diff --git a/xen/arch/arm/arch.mk b/xen/arch/arm/arch.mk
index c3ac443b3788..ba3f140e2ea7 100644
--- a/xen/arch/arm/arch.mk
+++ b/xen/arch/arm/arch.mk
@@ -26,3 +26,5 @@ ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
         LDFLAGS += --fix-cortex-a53-843419
     endif
 endif
+
+ALL_OBJS-y := arch/arm/$(TARGET_SUBARCH)/head.o $(ALL_OBJS-y)
diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index d7d2adc1881e..b469ec8f2452 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -123,37 +123,20 @@ $(TARGET): $(TARGET)-syms $(efi-y) boot/mkelf32
 
 CFLAGS-$(XEN_BUILD_EFI) += -DXEN_BUILD_EFI
 
-ALL_OBJS := $(BASEDIR)/arch/x86/boot/built_in.o $(BASEDIR)/arch/x86/efi/built_in.o $(ALL_OBJS)
-
-ifeq ($(CONFIG_LTO),y)
-# Gather all LTO objects together
-prelink_lto.o: $(ALL_OBJS) $(ALL_LIBS)
-	$(LD_LTO) -r -o $@ $(filter-out %.a,$^) --start-group $(filter %.a,$^) --end-group
-
-# Link it with all the binary objects
-prelink.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) prelink_lto.o FORCE
-	$(call if_changed,ld)
-else
-prelink.o: $(ALL_OBJS) $(ALL_LIBS) FORCE
-	$(call if_changed,ld)
-endif
-
-targets += prelink.o
-
-$(TARGET)-syms: prelink.o xen.lds
-	$(LD) $(XEN_LDFLAGS) -T xen.lds -N prelink.o $(build_id_linker) \
+$(TARGET)-syms: $(BASEDIR)/prelink.o xen.lds
+	$(LD) $(XEN_LDFLAGS) -T xen.lds -N $< $(build_id_linker) \
 	    $(BASEDIR)/common/symbols-dummy.o -o $(@D)/.$(@F).0
 	$(NM) -pa --format=sysv $(@D)/.$(@F).0 \
 		| $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort \
 		>$(@D)/.$(@F).0.S
 	$(MAKE) -f $(BASEDIR)/Rules.mk efi-y= $(@D)/.$(@F).0.o
-	$(LD) $(XEN_LDFLAGS) -T xen.lds -N prelink.o $(build_id_linker) \
+	$(LD) $(XEN_LDFLAGS) -T xen.lds -N $< $(build_id_linker) \
 	    $(@D)/.$(@F).0.o -o $(@D)/.$(@F).1
 	$(NM) -pa --format=sysv $(@D)/.$(@F).1 \
 		| $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort $(syms-warn-dup-y) \
 		>$(@D)/.$(@F).1.S
 	$(MAKE) -f $(BASEDIR)/Rules.mk efi-y= $(@D)/.$(@F).1.o
-	$(LD) $(XEN_LDFLAGS) -T xen.lds -N prelink.o $(build_id_linker) \
+	$(LD) $(XEN_LDFLAGS) -T xen.lds -N $< $(build_id_linker) \
 	    $(@D)/.$(@F).1.o -o $@
 	$(NM) -pa --format=sysv $(@D)/$(@F) \
 		| $(BASEDIR)/tools/symbols --all-symbols --xensyms --sysv --sort \
@@ -206,7 +189,7 @@ note_file_option ?= $(note_file)
 
 ifeq ($(XEN_BUILD_PE),y)
 extra-y += efi.lds
-$(TARGET).efi: prelink.o $(note_file) efi.lds efi/relocs-dummy.o efi/mkreloc
+$(TARGET).efi: $(BASEDIR)/prelink.o $(note_file) efi.lds efi/relocs-dummy.o efi/mkreloc
 ifeq ($(CONFIG_DEBUG_INFO),y)
 	$(if $(filter --strip-debug,$(EFI_LDFLAGS)),echo,:) "Will strip debug info from $(@F)"
 endif
@@ -235,7 +218,7 @@ $(TARGET).efi: FORCE
 	echo '$(if $(filter y,$(XEN_BUILD_EFI)),xen.efi generation,EFI support) disabled'
 endif
 
-efi/buildid.o efi/relocs-dummy.o: $(BASEDIR)/arch/x86/efi/built_in.o
+# These should already have been rebuilt when building the prerequisite of "prelink.o"
 efi/buildid.o efi/relocs-dummy.o: ;
 
 .PHONY: include
diff --git a/xen/arch/x86/arch.mk b/xen/arch/x86/arch.mk
index 19c9cd206ed0..c830dc5b3a7c 100644
--- a/xen/arch/x86/arch.mk
+++ b/xen/arch/x86/arch.mk
@@ -104,3 +104,5 @@ endif
 
 # Set up the assembler include path properly for older toolchains.
 CFLAGS += -Wa,-I$(BASEDIR)/include
+
+ALL_OBJS-y := arch/x86/boot/built_in.o arch/x86/efi/built_in.o $(ALL_OBJS-y)
diff --git a/xen/build.mk b/xen/build.mk
index 622e841c1cc0..740945333a97 100644
--- a/xen/build.mk
+++ b/xen/build.mk
@@ -58,3 +58,21 @@ arch/$(TARGET_ARCH)/include/asm/asm-offsets.h: asm-offsets.s
 	  sed -rne "/^[^#].*==>/{s:.*==>(.*)<==.*:\1:; s: [\$$#]: :; p;}"; \
 	  echo ""; \
 	  echo "#endif") <$< >$@
+
+ifeq ($(CONFIG_LTO),y)
+# Gather all LTO objects together
+prelink_lto.o: $(ALL_OBJS) $(ALL_LIBS)
+	$(LD_LTO) -r -o $@ $(filter-out %.a,$^) --start-group $(filter %.a,$^) --end-group
+
+# Link it with all the binary objects
+prelink.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) prelink_lto.o FORCE
+	$(call if_changed,ld)
+else
+prelink.o: $(ALL_OBJS) $(ALL_LIBS) FORCE
+	$(call if_changed,ld)
+endif
+
+targets += prelink.o
+
+$(TARGET): prelink.o FORCE
+	$(MAKE) -f $(BASEDIR)/Rules.mk -C arch/$(TARGET_ARCH) $@
-- 
Anthony PERARD
Re: [XEN PATCH v8 07/47] build: set ALL_OBJS to main Makefile; move prelink.o to main Makefile
Posted by Jan Beulich 2 years, 11 months ago 
On 25.11.2021 14:39, Anthony PERARD wrote:

Nit: In the title, do you mean "set ALL_OBJS in main Makefile; ..."?

> --- a/xen/Makefile
> +++ b/xen/Makefile
> @@ -285,8 +285,21 @@ CFLAGS += -flto
>  LDFLAGS-$(CONFIG_CC_IS_CLANG) += -plugin LLVMgold.so
>  endif
>  
> +# Note that link order matters!
> +ALL_OBJS-y                := common/built_in.o
> +ALL_OBJS-y                += drivers/built_in.o
> +ALL_OBJS-y                += lib/built_in.o
> +ALL_OBJS-y                += xsm/built_in.o
> +ALL_OBJS-y                += arch/$(TARGET_ARCH)/built_in.o
> +ALL_OBJS-$(CONFIG_CRYPTO) += crypto/built_in.o
> +
> +ALL_LIBS-y                := lib/lib.a
> +
>  include $(BASEDIR)/arch/$(TARGET_ARCH)/arch.mk
>  
> +export ALL_OBJS := $(ALL_OBJS-y)
> +export ALL_LIBS := $(ALL_LIBS-y)

Who's the consumer of these exports? I ask because I don't consider the
names very suitable for exporting, and hence I'd prefer to see their
scope limited. If e.g. it's only a single make invocation where they
need propagating, doing so on the command line might be better.

> --- a/xen/arch/arm/Rules.mk
> +++ b/xen/arch/arm/Rules.mk
> @@ -0,0 +1,5 @@
> +# head.o is built by descending into arch/arm/$(TARGET_SUBARCH), depends on the
> +# part of $(ALL_OBJS) that will eventually recurse into $(TARGET_SUBARCH)/ and
> +# build head.o
> +arch/arm/$(TARGET_SUBARCH)/head.o: arch/arm/built_in.o
> +arch/arm/$(TARGET_SUBARCH)/head.o: ;

Can't this be a single line:

arch/arm/$(TARGET_SUBARCH)/head.o: arch/arm/built_in.o ;

?

> @@ -235,7 +218,7 @@ $(TARGET).efi: FORCE
>  	echo '$(if $(filter y,$(XEN_BUILD_EFI)),xen.efi generation,EFI support) disabled'
>  endif
>  
> -efi/buildid.o efi/relocs-dummy.o: $(BASEDIR)/arch/x86/efi/built_in.o
> +# These should already have been rebuilt when building the prerequisite of "prelink.o"
>  efi/buildid.o efi/relocs-dummy.o: ;

If the comment is true in all cases, do they really still need an empty
rule?

Jan
Re: [XEN PATCH v8 07/47] build: set ALL_OBJS to main Makefile; move prelink.o to main Makefile
Posted by Anthony PERARD 2 years, 11 months ago 
On Mon, Dec 06, 2021 at 05:52:51PM +0100, Jan Beulich wrote:
> On 25.11.2021 14:39, Anthony PERARD wrote:
> 
> Nit: In the title, do you mean "set ALL_OBJS in main Makefile; ..."?
> 
> > --- a/xen/Makefile
> > +++ b/xen/Makefile
> > @@ -285,8 +285,21 @@ CFLAGS += -flto
> >  LDFLAGS-$(CONFIG_CC_IS_CLANG) += -plugin LLVMgold.so
> >  endif
> >  
> > +# Note that link order matters!
> > +ALL_OBJS-y                := common/built_in.o
> > +ALL_OBJS-y                += drivers/built_in.o
> > +ALL_OBJS-y                += lib/built_in.o
> > +ALL_OBJS-y                += xsm/built_in.o
> > +ALL_OBJS-y                += arch/$(TARGET_ARCH)/built_in.o
> > +ALL_OBJS-$(CONFIG_CRYPTO) += crypto/built_in.o
> > +
> > +ALL_LIBS-y                := lib/lib.a
> > +
> >  include $(BASEDIR)/arch/$(TARGET_ARCH)/arch.mk
> >  
> > +export ALL_OBJS := $(ALL_OBJS-y)
> > +export ALL_LIBS := $(ALL_LIBS-y)
> 
> Who's the consumer of these exports? I ask because I don't consider the
> names very suitable for exporting, and hence I'd prefer to see their
> scope limited. If e.g. it's only a single make invocation where they
> need propagating, doing so on the command line might be better.

There seems to be only one consumer, "build.mk", and only the last
$(MAKE) call in the recipe "$(TARGET)". So, it's probably fine to set
both on the command line instead of using export. I'll have a look.

> > --- a/xen/arch/arm/Rules.mk
> > +++ b/xen/arch/arm/Rules.mk
> > @@ -0,0 +1,5 @@
> > +# head.o is built by descending into arch/arm/$(TARGET_SUBARCH), depends on the
> > +# part of $(ALL_OBJS) that will eventually recurse into $(TARGET_SUBARCH)/ and
> > +# build head.o
> > +arch/arm/$(TARGET_SUBARCH)/head.o: arch/arm/built_in.o
> > +arch/arm/$(TARGET_SUBARCH)/head.o: ;
> 
> Can't this be a single line:
> 
> arch/arm/$(TARGET_SUBARCH)/head.o: arch/arm/built_in.o ;

Sure.

> > @@ -235,7 +218,7 @@ $(TARGET).efi: FORCE
> >  	echo '$(if $(filter y,$(XEN_BUILD_EFI)),xen.efi generation,EFI support) disabled'
> >  endif
> >  
> > -efi/buildid.o efi/relocs-dummy.o: $(BASEDIR)/arch/x86/efi/built_in.o
> > +# These should already have been rebuilt when building the prerequisite of "prelink.o"
> >  efi/buildid.o efi/relocs-dummy.o: ;
> 
> If the comment is true in all cases, do they really still need an empty
> rule?

Yes. Those two targets are unfortunately a prerequisite of "xen.efi", so
make will look for a rule to make them, and would use %.o:%.c without
this explicit rule.

Thanks,

-- 
Anthony PERARD

Patchew 2.1-devel-b67e4c2

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