lib: collect library files in an archive

In order to (subsequently) drop odd things like CONFIG_NEEDS_LIST_SORT
just to avoid bloating binaries when only some arch-es and/or
configurations need generic library routines, combine objects under lib/
into an archive, which the linker then can pick the necessary objects
out of.

Note that we can't use thin archives just yet, until we've raised the
minimum required binutils version suitably.

Note further that --start-group / --end-group get put in place right
away to allow for symbol resolution across all archives, once we gain
multuiple ones.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wl@xen.org>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>

diff --git a/xen/Rules.mk b/xen/Rules.mk
index d5e5eb33de391a5d38262f45c17f36556f550037..aba6ca2a90f5aad049f624525d82a64290910688 100644 (file)
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -41,12 +41,16 @@ 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, \
@@ -60,7 +64,14 @@ include Makefile
 # ---------------------------------------------------------------------------
 
 quiet_cmd_ld = LD      $@
-cmd_ld = $(LD) $(XEN_LDFLAGS) -r -o $@ $(real-prereqs)
+cmd_ld = $(LD) $(XEN_LDFLAGS) -r -o $@ $(filter-out %.a,$(real-prereqs)) \
+               --start-group $(filter %.a,$(real-prereqs)) --end-group
+
+# Archive
+# ---------------------------------------------------------------------------
+
+quiet_cmd_ar = AR      $@
+cmd_ar = rm -f $@; $(AR) cPrs $@ $(real-prereqs)
 
 # Objcopy
 # ---------------------------------------------------------------------------
@@ -86,6 +97,10 @@ obj-y    := $(patsubst %/, %/built_in.o, $(obj-y))
 # tell kbuild to descend
 subdir-obj-y := $(filter %/built_in.o, $(obj-y))
 
+# Libraries are always collected in one lib file.
+# Filter out objects already built-in
+lib-y := $(filter-out $(obj-y), $(sort $(lib-y)))
+
 $(filter %.init.o,$(obj-y) $(obj-bin-y) $(extra-y)): CFLAGS-y += -DINIT_SECTIONS_ONLY
 
 ifeq ($(CONFIG_COVERAGE),y)
@@ -129,7 +144,7 @@ include $(BASEDIR)/arch/$(TARGET_ARCH)/Rules.mk
 c_flags += $(CFLAGS-y)
 a_flags += $(CFLAGS-y) $(AFLAGS-y)
 
-built_in.o: $(obj-y) $(extra-y)
+built_in.o: $(obj-y) $(if $(strip $(lib-y)),lib.a) $(extra-y)
 ifeq ($(strip $(obj-y)),)
        $(CC) $(c_flags) -c -x c /dev/null -o $@
 else
@@ -140,8 +155,14 @@ else
 endif
 endif
 
+lib.a: $(lib-y) FORCE
+       $(call if_changed,ar)
+
 targets += built_in.o
-targets += $(filter-out $(subdir-obj-y), $(obj-y)) $(extra-y)
+ifneq ($(strip $(lib-y)),)
+targets += lib.a
+endif
+targets += $(filter-out $(subdir-obj-y), $(obj-y) $(lib-y)) $(extra-y)
 targets += $(MAKECMDGOALS)
 
 built_in_bin.o: $(obj-bin-y) $(extra-y)
@@ -155,7 +176,7 @@ endif
 PHONY += FORCE
 FORCE:
 
-%/built_in.o: FORCE
+%/built_in.o %/lib.a: FORCE
        $(MAKE) -f $(BASEDIR)/Rules.mk -C $* built_in.o
 
 %/built_in_bin.o: FORCE

diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index ad2d497c456fd7ebc2c38e8cf446d1c7f16f528f..512ffdd781718e0a6e180e6402f9928e62f808d8 100644 (file)
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -90,14 +90,14 @@ endif
 
 ifeq ($(CONFIG_LTO),y)
 # Gather all LTO objects together
-prelink_lto.o: $(ALL_OBJS)
-       $(LD_LTO) -r -o $@ $^
+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) FORCE
+prelink.o: $(ALL_OBJS) $(ALL_LIBS) FORCE
        $(call if_changed,ld)
 endif
 

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 9b368632fb43742937ef80c58182aabe76466e58..8f2180485b2b4e33328c39de2fd935c852d901e7 100644 (file)
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -132,8 +132,8 @@ EFI_OBJS-$(XEN_BUILD_EFI) := efi/relocs-dummy.o
 
 ifeq ($(CONFIG_LTO),y)
 # Gather all LTO objects together
-prelink_lto.o: $(ALL_OBJS)
-       $(LD_LTO) -r -o $@ $^
+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 $(EFI_OBJS-y) FORCE
@@ -142,10 +142,10 @@ prelink.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) prelink_lto.o $
 prelink-efi.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) prelink_lto.o FORCE
        $(call if_changed,ld)
 else
-prelink.o: $(ALL_OBJS) $(EFI_OBJS-y) FORCE
+prelink.o: $(ALL_OBJS) $(ALL_LIBS) $(EFI_OBJS-y) FORCE
        $(call if_changed,ld)
 
-prelink-efi.o: $(ALL_OBJS) FORCE
+prelink-efi.o: $(ALL_OBJS) $(ALL_LIBS) FORCE
        $(call if_changed,ld)
 endif
 

diff --git a/xen/lib/Makefile b/xen/lib/Makefile
index 53b1da025e0d681169d4981abf53a4529d5c22c7..b8814361d63e93676b8588f6dd3b256e47e9f727 100644 (file)
--- a/xen/lib/Makefile
+++ b/xen/lib/Makefile
@@ -1,2 +1,3 @@
-obj-y += ctype.o
 obj-$(CONFIG_X86) += x86/
+
+lib-y += ctype.o