* [PATCH 1/2] kbuild: remove top-level built-in.a
@ 2019-01-14 3:27 Masahiro Yamada
2019-01-14 3:27 ` [PATCH 2/2] kbuild: merge KBUILD_VMLINUX_{INIT,MAIN} into KBUILD_VMLINUX_OBJS Masahiro Yamada
2019-01-15 7:15 ` [PATCH 1/2] kbuild: remove top-level built-in.a Nicholas Piggin
0 siblings, 2 replies; 5+ messages in thread
From: Masahiro Yamada @ 2019-01-14 3:27 UTC (permalink / raw)
To: linux-kbuild
Cc: Nicholas Piggin, Stephen Rothwell, Masahiro Yamada, linux-kernel
The symbol table in the final archive is unneeded because it is passed
to the linker after the --whole-archive option. Every object file in
the archive is included in the link anyway.
Pass thin archives from subdirectories directly to the linker, and
remove the final archiving step.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
scripts/link-vmlinux.sh | 30 ++++++------------------------
1 file changed, 6 insertions(+), 24 deletions(-)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index c8cf453..4788def 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -44,24 +44,6 @@ info()
fi
}
-# Thin archive build here makes a final archive with symbol table and indexes
-# from vmlinux objects INIT and MAIN, which can be used as input to linker.
-# KBUILD_VMLINUX_LIBS archives should already have symbol table and indexes
-# added.
-#
-# Traditional incremental style of link does not require this step
-#
-# built-in.a output file
-#
-archive_builtin()
-{
- info AR built-in.a
- rm -f built-in.a;
- ${AR} rcsTP${KBUILD_ARFLAGS} built-in.a \
- ${KBUILD_VMLINUX_INIT} \
- ${KBUILD_VMLINUX_MAIN}
-}
-
# Link of vmlinux.o used for section mismatch analysis
# ${1} output file
modpost_link()
@@ -69,7 +51,8 @@ modpost_link()
local objects
objects="--whole-archive \
- built-in.a \
+ ${KBUILD_VMLINUX_INIT} \
+ ${KBUILD_VMLINUX_MAIN} \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
@@ -88,7 +71,8 @@ vmlinux_link()
if [ "${SRCARCH}" != "um" ]; then
objects="--whole-archive \
- built-in.a \
+ ${KBUILD_VMLINUX_INIT} \
+ ${KBUILD_VMLINUX_MAIN} \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
@@ -99,7 +83,8 @@ vmlinux_link()
-T ${lds} ${objects}
else
objects="-Wl,--whole-archive \
- built-in.a \
+ ${KBUILD_VMLINUX_INIT} \
+ ${KBUILD_VMLINUX_MAIN} \
-Wl,--no-whole-archive \
-Wl,--start-group \
${KBUILD_VMLINUX_LIBS} \
@@ -160,7 +145,6 @@ cleanup()
rm -f .tmp_System.map
rm -f .tmp_kallsyms*
rm -f .tmp_vmlinux*
- rm -f built-in.a
rm -f System.map
rm -f vmlinux
rm -f vmlinux.o
@@ -217,8 +201,6 @@ fi;
# final build of init/
${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
-archive_builtin
-
#link vmlinux.o
info LD vmlinux.o
modpost_link vmlinux.o
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 2/2] kbuild: merge KBUILD_VMLINUX_{INIT,MAIN} into KBUILD_VMLINUX_OBJS
2019-01-14 3:27 [PATCH 1/2] kbuild: remove top-level built-in.a Masahiro Yamada
@ 2019-01-14 3:27 ` Masahiro Yamada
2019-01-15 7:15 ` [PATCH 1/2] kbuild: remove top-level built-in.a Nicholas Piggin
1 sibling, 0 replies; 5+ messages in thread
From: Masahiro Yamada @ 2019-01-14 3:27 UTC (permalink / raw)
To: linux-kbuild
Cc: Nicholas Piggin, Stephen Rothwell, Masahiro Yamada, Michal Marek,
linux-kernel
The top Makefile does not need to export KBUILD_VMLINUX_INIT and
KBUILD_VMLINUX_MAIN separately.
Put every built-in.a into KBUILD_VMLINUX_OBJS. The order of
$(head-y), $(init-y), $(core-y), ... is still retained.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---
Makefile | 6 +++---
scripts/link-vmlinux.sh | 28 ++++++++++------------------
2 files changed, 13 insertions(+), 21 deletions(-)
diff --git a/Makefile b/Makefile
index 499b968..68898cc 100644
--- a/Makefile
+++ b/Makefile
@@ -975,15 +975,15 @@ libs-y2 := $(patsubst %/, %/built-in.a, $(filter-out %.a, $(libs-y)))
virt-y := $(patsubst %/, %/built-in.a, $(virt-y))
# Externally visible symbols (used by link-vmlinux.sh)
-export KBUILD_VMLINUX_INIT := $(head-y) $(init-y)
-export KBUILD_VMLINUX_MAIN := $(core-y) $(libs-y2) $(drivers-y) $(net-y) $(virt-y)
+export KBUILD_VMLINUX_OBJS := $(head-y) $(init-y) $(core-y) $(libs-y2) \
+ $(drivers-y) $(net-y) $(virt-y)
export KBUILD_VMLINUX_LIBS := $(libs-y1)
export KBUILD_LDS := arch/$(SRCARCH)/kernel/vmlinux.lds
export LDFLAGS_vmlinux
# used by scripts/package/Makefile
export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) arch Documentation include samples scripts tools)
-vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN) $(KBUILD_VMLINUX_LIBS)
+vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)
# Recurse until adjust_autoksyms.sh is satisfied
PHONY += autoksyms_recursive
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 4788def..bc7f1fc 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -3,22 +3,17 @@
#
# link vmlinux
#
-# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_INIT) and
-# $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.a files
-# from top-level directories in the kernel tree, others are specified in
-# arch/$(ARCH)/Makefile. Ordering when linking is important, and
-# $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
-# which are linked conditionally (not within --whole-archive), and do not
-# require symbol indexes added.
+# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_OBJS) and
+# $(KBUILD_VMLINUX_LIBS). Most are built-in.a files from top-level directories
+# in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
+# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
+# (not within --whole-archive), and do not require symbol indexes added.
#
# vmlinux
# ^
# |
-# +-< $(KBUILD_VMLINUX_INIT)
-# | +--< init/version.o + more
-# |
-# +--< $(KBUILD_VMLINUX_MAIN)
-# | +--< drivers/built-in.a mm/built-in.a + more
+# +--< $(KBUILD_VMLINUX_OBJS)
+# | +--< init/built-in.a drivers/built-in.a mm/built-in.a + more
# |
# +--< $(KBUILD_VMLINUX_LIBS)
# | +--< lib/lib.a + more
@@ -51,8 +46,7 @@ modpost_link()
local objects
objects="--whole-archive \
- ${KBUILD_VMLINUX_INIT} \
- ${KBUILD_VMLINUX_MAIN} \
+ ${KBUILD_VMLINUX_OBJS} \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
@@ -71,8 +65,7 @@ vmlinux_link()
if [ "${SRCARCH}" != "um" ]; then
objects="--whole-archive \
- ${KBUILD_VMLINUX_INIT} \
- ${KBUILD_VMLINUX_MAIN} \
+ ${KBUILD_VMLINUX_OBJS} \
--no-whole-archive \
--start-group \
${KBUILD_VMLINUX_LIBS} \
@@ -83,8 +76,7 @@ vmlinux_link()
-T ${lds} ${objects}
else
objects="-Wl,--whole-archive \
- ${KBUILD_VMLINUX_INIT} \
- ${KBUILD_VMLINUX_MAIN} \
+ ${KBUILD_VMLINUX_OBJS} \
-Wl,--no-whole-archive \
-Wl,--start-group \
${KBUILD_VMLINUX_LIBS} \
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH 1/2] kbuild: remove top-level built-in.a
2019-01-14 3:27 [PATCH 1/2] kbuild: remove top-level built-in.a Masahiro Yamada
2019-01-14 3:27 ` [PATCH 2/2] kbuild: merge KBUILD_VMLINUX_{INIT,MAIN} into KBUILD_VMLINUX_OBJS Masahiro Yamada
@ 2019-01-15 7:15 ` Nicholas Piggin
2019-01-15 9:01 ` Masahiro Yamada
1 sibling, 1 reply; 5+ messages in thread
From: Nicholas Piggin @ 2019-01-15 7:15 UTC (permalink / raw)
To: linux-kbuild, Masahiro Yamada; +Cc: linux-kernel, Stephen Rothwell
Masahiro Yamada's on January 14, 2019 1:27 pm:
> The symbol table in the final archive is unneeded because it is passed
> to the linker after the --whole-archive option. Every object file in
> the archive is included in the link anyway.
>
> Pass thin archives from subdirectories directly to the linker, and
> remove the final archiving step.
This seems like a good improvement. As far as I remember, it was slower
to do the final link without the index built. Maybe I was testing it
in a revision before moving those files into --whole-archive? If there
is no slowdown, then I have no objection.
Acked-by: Nicholas Piggin <npiggin@gmail.com>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH 1/2] kbuild: remove top-level built-in.a
2019-01-15 7:15 ` [PATCH 1/2] kbuild: remove top-level built-in.a Nicholas Piggin
@ 2019-01-15 9:01 ` Masahiro Yamada
2019-01-23 8:26 ` Nicholas Piggin
0 siblings, 1 reply; 5+ messages in thread
From: Masahiro Yamada @ 2019-01-15 9:01 UTC (permalink / raw)
To: Nicholas Piggin
Cc: Linux Kbuild mailing list, Linux Kernel Mailing List, Stephen Rothwell
Hi Nicholas,
On Tue, Jan 15, 2019 at 5:07 PM Nicholas Piggin <npiggin@gmail.com> wrote:
>
> Masahiro Yamada's on January 14, 2019 1:27 pm:
> > The symbol table in the final archive is unneeded because it is passed
> > to the linker after the --whole-archive option. Every object file in
> > the archive is included in the link anyway.
> >
> > Pass thin archives from subdirectories directly to the linker, and
> > remove the final archiving step.
>
> This seems like a good improvement. As far as I remember, it was slower
> to do the final link without the index built. Maybe I was testing it
> in a revision before moving those files into --whole-archive? If there
> is no slowdown, then I have no objection.
Thanks for the review.
I measured the performance of scripts/link-vmlinux.sh with 'perf stat'.
(20 times for each)
Before this patch:
Performance counter stats for 'make vmlinux' (20 runs):
5.266796537 seconds time elapsed
( +- 0.12% )
After this patch:
Performance counter stats for 'make vmlinux' (20 runs):
4.945576395 seconds time elapsed
So, the performance is slightly better.
Maybe, does omitting the 'ar' save some time?
Anyway, this commit is good.
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH 1/2] kbuild: remove top-level built-in.a
2019-01-15 9:01 ` Masahiro Yamada
@ 2019-01-23 8:26 ` Nicholas Piggin
0 siblings, 0 replies; 5+ messages in thread
From: Nicholas Piggin @ 2019-01-23 8:26 UTC (permalink / raw)
To: Masahiro Yamada
Cc: Linux Kbuild mailing list, Linux Kernel Mailing List, Stephen Rothwell
Masahiro Yamada's on January 15, 2019 7:01 pm:
> Hi Nicholas,
>
>
> On Tue, Jan 15, 2019 at 5:07 PM Nicholas Piggin <npiggin@gmail.com> wrote:
>>
>> Masahiro Yamada's on January 14, 2019 1:27 pm:
>> > The symbol table in the final archive is unneeded because it is passed
>> > to the linker after the --whole-archive option. Every object file in
>> > the archive is included in the link anyway.
>> >
>> > Pass thin archives from subdirectories directly to the linker, and
>> > remove the final archiving step.
>>
>> This seems like a good improvement. As far as I remember, it was slower
>> to do the final link without the index built. Maybe I was testing it
>> in a revision before moving those files into --whole-archive? If there
>> is no slowdown, then I have no objection.
>
>
> Thanks for the review.
>
>
> I measured the performance of scripts/link-vmlinux.sh with 'perf stat'.
> (20 times for each)
>
>
>
> Before this patch:
>
> Performance counter stats for 'make vmlinux' (20 runs):
>
> 5.266796537 seconds time elapsed
> ( +- 0.12% )
>
>
>
> After this patch:
>
> Performance counter stats for 'make vmlinux' (20 runs):
>
> 4.945576395 seconds time elapsed
>
>
>
>
> So, the performance is slightly better.
>
> Maybe, does omitting the 'ar' save some time?
Wow yeah that's a good speedup and simplification to boot. Thanks for
checking it.
> Anyway, this commit is good.
Yes, it's a good improvement.
Thanks,
Nick
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-01-23 8:26 UTC | newest]
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