Mailing List Archive: [PATCH v2 2/8] lib: collect library files in an archive

[PATCH v2 2/8] lib: collect library files in an archive

Oct 23, 2020, 3:17 AM

Post #1 of 5 (82 views)

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.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
xen/Rules.mk | 33 +++++++++++++++++++++++++++------
xen/arch/arm/Makefile | 6 +++---
xen/arch/x86/Makefile | 8 ++++----
xen/lib/Makefile | 3 ++-
4 files changed, 36 insertions(+), 14 deletions(-)

diff --git a/xen/Rules.mk b/xen/Rules.mk
index 333e19bec343..e59c7f213f77 100644
--- 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)
@@ -129,19 +144,25 @@ 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) $(extra-y)
ifeq ($(obj-y),)
$(CC) $(c_flags) -c -x c /dev/null -o $@
else
ifeq ($(CONFIG_LTO),y)
- $(LD_LTO) -r -o $@ $(filter-out $(extra-y),$^)
+ $(LD_LTO) -r -o $@ $(filter-out lib.a $(extra-y),$^)
else
- $(LD) $(XEN_LDFLAGS) -r -o $@ $(filter-out $(extra-y),$^)
+ $(LD) $(XEN_LDFLAGS) -r -o $@ $(filter-out lib.a $(extra-y),$^)
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 296c5e68bbc3..612a83b315c8 100644
--- 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 9b368632fb43..8f2180485b2b 100644
--- 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 53b1da025e0d..b8814361d63e 100644
--- a/xen/lib/Makefile
+++ b/xen/lib/Makefile
@@ -1,2 +1,3 @@
-obj-y += ctype.o
obj-$(CONFIG_X86) += x86/
+
+lib-y += ctype.o
--
2.22.0

Re: [PATCH v2 2/8] lib: collect library files in an archive [ In reply to ]

julien at xen

Nov 18, 2020, 9:06 AM

Post #2 of 5 (82 views)

Permalink

(+ Anthony)

Hi Jan,

On 23/10/2020 11:17, Jan Beulich wrote:
> 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.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> xen/Rules.mk | 33 +++++++++++++++++++++++++++------
> xen/arch/arm/Makefile | 6 +++---
> xen/arch/x86/Makefile | 8 ++++----
> xen/lib/Makefile | 3 ++-

IIRC, Anthony worked on the build systems. If I am right, it would be
good to get a review from him.

> 4 files changed, 36 insertions(+), 14 deletions(-)
>
> diff --git a/xen/Rules.mk b/xen/Rules.mk
> index 333e19bec343..e59c7f213f77 100644
> --- 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)
> @@ -129,19 +144,25 @@ 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) $(extra-y)
> ifeq ($(obj-y),)
> $(CC) $(c_flags) -c -x c /dev/null -o $@
> else
> ifeq ($(CONFIG_LTO),y)
> - $(LD_LTO) -r -o $@ $(filter-out $(extra-y),$^)
> + $(LD_LTO) -r -o $@ $(filter-out lib.a $(extra-y),$^)
> else
> - $(LD) $(XEN_LDFLAGS) -r -o $@ $(filter-out $(extra-y),$^)
> + $(LD) $(XEN_LDFLAGS) -r -o $@ $(filter-out lib.a $(extra-y),$^)
> 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 $* built_in.o
>
> %/built_in_bin.o: FORCE
> diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
> index 296c5e68bbc3..612a83b315c8 100644
> --- a/xen/arch/arm/Makefile
> +++ b/xen/arch/arm/Makefile
> @@ -90,14 +90,14 @@ endif
>
> ifeq ($(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
> $(call if_changed,ld)
> endif
>
> diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
> index 9b368632fb43..8f2180485b2b 100644
> --- a/xen/arch/x86/Makefile
> +++ b/xen/arch/x86/Makefile
> @@ -132,8 +132,8 @@ EFI_OBJS-$(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
> $(call if_changed,ld)
> endif
>
> diff --git a/xen/lib/Makefile b/xen/lib/Makefile
> index 53b1da025e0d..b8814361d63e 100644
> --- a/xen/lib/Makefile
> +++ b/xen/lib/Makefile
> @@ -1,2 +1,3 @@
> -obj-y += ctype.o
> obj-$(CONFIG_X86) += x86/
> +
> +lib-y += ctype.o

May I ask why all the code movement by ctype was done after this patch?

Cheers,

--
Julien Grall

Re: [PATCH v2 2/8] lib: collect library files in an archive [ In reply to ]

julien at xen

Nov 18, 2020, 9:31 AM

Post #3 of 5 (82 views)

Permalink

Hi Jan,

On 23/10/2020 11:17, Jan Beulich wrote:
> 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.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> xen/Rules.mk | 33 +++++++++++++++++++++++++++------
> xen/arch/arm/Makefile | 6 +++---
> xen/arch/x86/Makefile | 8 ++++----
> xen/lib/Makefile | 3 ++-
> 4 files changed, 36 insertions(+), 14 deletions(-)

I can't build Xen on Arm after this patch:

AR lib.a
aarch64-linux-gnu-ld -EL -r -o built_in.o
aarch64-linux-gnu-ld: no input files
/home/ANT.AMAZON.COM/jgrall/works/oss/xen/xen/Rules.mk:154: recipe for
target 'built_in.o' failed

Cheers,

--
Julien Grall

Re: [PATCH v2 2/8] lib: collect library files in an archive [ In reply to ]

jbeulich at suse

Nov 19, 2020, 2:15 AM

Post #4 of 5 (82 views)

Permalink

On 18.11.2020 18:06, Julien Grall wrote:
> On 23/10/2020 11:17, Jan Beulich wrote:
>> 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.
>>
>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>> ---
>> xen/Rules.mk | 33 +++++++++++++++++++++++++++------
>> xen/arch/arm/Makefile | 6 +++---
>> xen/arch/x86/Makefile | 8 ++++----
>> xen/lib/Makefile | 3 ++-
>
> IIRC, Anthony worked on the build systems. If I am right, it would be
> good to get a review from him.

I'll try to remember next time round.

>> --- a/xen/lib/Makefile
>> +++ b/xen/lib/Makefile
>> @@ -1,2 +1,3 @@
>> -obj-y += ctype.o
>> obj-$(CONFIG_X86) += x86/
>> +
>> +lib-y += ctype.o
>
> May I ask why all the code movement by ctype was done after this patch?

I'm sorry, but I'm afraid I don't understand the question.

Jan

Re: [PATCH v2 2/8] lib: collect library files in an archive [ In reply to ]

jbeulich at suse

Nov 19, 2020, 2:44 AM

Post #5 of 5 (82 views)

Permalink

On 18.11.2020 18:31, Julien Grall wrote:
> On 23/10/2020 11:17, Jan Beulich wrote:
>> 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.
>>
>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>> ---
>> xen/Rules.mk | 33 +++++++++++++++++++++++++++------
>> xen/arch/arm/Makefile | 6 +++---
>> xen/arch/x86/Makefile | 8 ++++----
>> xen/lib/Makefile | 3 ++-
>> 4 files changed, 36 insertions(+), 14 deletions(-)
>
> I can't build Xen on Arm after this patch:
>
> AR lib.a
> aarch64-linux-gnu-ld -EL -r -o built_in.o
> aarch64-linux-gnu-ld: no input files
> /home/ANT.AMAZON.COM/jgrall/works/oss/xen/xen/Rules.mk:154: recipe for
> target 'built_in.o' failed

Oh, indeed, this triggers a pre-existing bug. I didn't notice it
because for Arm I build-tested only the series as a whole. Will
add a fix for the issue as prereq patch.

Thanks for noticing,
Jan