diff mbox series

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

Message ID 78dccec2-064f-d4b1-1865-eb3f1f14247a@suse.com (mailing list archive)
State Superseded
Headers show
Series xen: beginnings of moving library-like code into an archive | expand

Commit Message

Jan Beulich Oct. 23, 2020, 10:17 a.m. UTC 
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(-)

Comments

Julien Grall Nov. 18, 2020, 5:06 p.m. UTC | #1 
(+ 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 Nov. 18, 2020, 5:31 p.m. UTC | #2 
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,
Jan Beulich Nov. 19, 2020, 10:15 a.m. UTC | #3 
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
Jan Beulich Nov. 19, 2020, 10:44 a.m. UTC | #4 
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
diff mbox series

Patch

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