* [Buildroot] [PATCH 1/2] build: add support for as-needed linking
@ 2016-07-17 15:05 gustavo.zacarias at free-electrons.com
2016-07-17 15:05 ` [Buildroot] [PATCH 2/2] docs/manual: document PKG_AS_NEEDED gustavo.zacarias at free-electrons.com
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: gustavo.zacarias at free-electrons.com @ 2016-07-17 15:05 UTC (permalink / raw)
To: buildroot
From: Gustavo Zacarias <gustavo.zacarias@free-electrons.com>
This option tells the linker to only link to the libraries containing
symbols that are actually used.
It requires libtool patches to fully clean the needed chain, these are
used by major distributions such as Debian and Gentoo.
https://wiki.debian.org/ToolChain/DSOLinking
https://wiki.gentoo.org/wiki/Project:Quality_Assurance/As-needed
Introduce a BR2_AS_NEEDED global enable option (default=no, marked as
experimental) that generally disables the libtool patching and avoids
the extra LDFLAGS (-Wl,--as-needed).
Also add a per-package PACKAGE_AS_NEEDED (default=yes) option to work
around problematic packages that might not behave too well with
as-needed linking.
For the libtool patching use a guess (automatic) method since
version-matching doesn't work accurately with some packages that ship
patched/modified ltmain.sh scripts, normally based on 2.4. In some of
these cases the as-needed-v2.2.6.patch works, and in other cases the
as-needed-v2.4.2.patch is necessary and the exact condition can't be
found in a deterministic way. If for some reason none of the patches
applies to a particular package this will only affect said package and
shouldn't have any consequence even if passing -Wl,--as-needed LDFLAGS.
Example for a simple defconfig:
BR2_arm=y
BR2_AS_NEEDED=y
BR2_TOOLCHAIN_EXTERNAL=y
BR2_PACKAGE_GSTREAMER1=y
BR2_PACKAGE_GST1_PLUGINS_BAD=y
With as-needed disabled:
$ readelf -a libgstbadvideo-1.0.so|grep "(NEEDED)"|wc -l
10
With as-needed enabled:
$ readelf -a libgstbadvideo-1.0.so|grep "(NEEDED)"|wc -l
8
Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com>
---
Config.in | 6 +++++
package/Makefile.in | 5 ++++
package/pkg-autotools.mk | 43 ++++++++++++++++++++++++++++++
support/libtool/as-needed-v1.5.26.patch | 46 +++++++++++++++++++++++++++++++++
support/libtool/as-needed-v1.5.patch | 38 +++++++++++++++++++++++++++
support/libtool/as-needed-v2.2.6.patch | 46 +++++++++++++++++++++++++++++++++
support/libtool/as-needed-v2.4.2.patch | 46 +++++++++++++++++++++++++++++++++
support/libtool/as-needed-v2.4.3.patch | 46 +++++++++++++++++++++++++++++++++
8 files changed, 276 insertions(+)
create mode 100644 support/libtool/as-needed-v1.5.26.patch
create mode 100644 support/libtool/as-needed-v1.5.patch
create mode 100644 support/libtool/as-needed-v2.2.6.patch
create mode 100644 support/libtool/as-needed-v2.4.2.patch
create mode 100644 support/libtool/as-needed-v2.4.3.patch
diff --git a/Config.in b/Config.in
index 7bb2a01..e8b0477 100644
--- a/Config.in
+++ b/Config.in
@@ -739,6 +739,12 @@ config BR2_REPRODUCIBLE
This is labeled as an experimental feature, as not all
packages behave properly to ensure reproducibility.
+config BR2_AS_NEEDED
+ bool "Link target binaries/libraries as-needed (experimental)"
+ help
+ Tell the linker to link in the produced binary/library only
+ the libraries containing symbols that are actually used.
+
endmenu
source "toolchain/Config.in"
diff --git a/package/Makefile.in b/package/Makefile.in
index afd5d3a..b190363 100644
--- a/package/Makefile.in
+++ b/package/Makefile.in
@@ -144,6 +144,11 @@ TARGET_CXXFLAGS = $(TARGET_CFLAGS)
TARGET_FCFLAGS = $(TARGET_ABI) $(TARGET_OPTIMIZATION) $(TARGET_DEBUGGING)
TARGET_LDFLAGS = $(call qstrip,$(BR2_TARGET_LDFLAGS))
+# $(PKG)_AS_NEEDED gets expanded too early for ifeq usage, so use subst instead
+ifeq ($(BR2_AS_NEEDED),y)
+TARGET_LDFLAGS += -Wl,$(subst NO,--no,$(subst YES,-,$($(PKG)_AS_NEEDED)))-as-needed
+endif
+
ifeq ($(BR2_BINFMT_FLAT),y)
TARGET_CFLAGS += $(if $($(PKG)_FLAT_STACKSIZE),-Wl$(comma)-elf2flt=-s$($(PKG)_FLAT_STACKSIZE),\
-Wl$(comma)-elf2flt)
diff --git a/package/pkg-autotools.mk b/package/pkg-autotools.mk
index 75e2df0..de00628 100644
--- a/package/pkg-autotools.mk
+++ b/package/pkg-autotools.mk
@@ -55,6 +55,26 @@ define UPDATE_CONFIG_HOOK
endef
#
+# Hook to patch libtool to make it work properly for as-needed linking
+#
+define LIBTOOL_AS_NEEDED_PATCH_HOOK
+ @$(call MESSAGE,"Patching libtool as-needed")
+ $(Q)for i in `find $($(PKG)_SRCDIR) -name ltmain.sh`; do \
+ if patch -p1 --dry-run -f -s -d $${i%/*} <support/libtool/as-needed-v2.4.3.patch >/dev/null ; then\
+ $(APPLY_PATCHES) $${i%/*} support/libtool as-needed-v2.4.3.patch; \
+ elif patch -p1 --dry-run -f -s -d $${i%/*} <support/libtool/as-needed-v2.4.2.patch >/dev/null ; then\
+ $(APPLY_PATCHES) $${i%/*} support/libtool as-needed-v2.4.2.patch; \
+ elif patch -p1 --dry-run -f -s -d $${i%/*} <support/libtool/as-needed-v2.2.6.patch >/dev/null ; then\
+ $(APPLY_PATCHES) $${i%/*} support/libtool as-needed-v2.2.6.patch; \
+ elif patch -p1 --dry-run -f -s -d $${i%/*} <support/libtool/as-needed-v1.5.26.patch >/dev/null ; then\
+ $(APPLY_PATCHES) $${i%/*} support/libtool as-needed-v1.5.26.patch; \
+ elif patch -p1 --dry-run -f -s -d $${i%/*} <support/libtool/as-needed-v1.5.patch >/dev/null ; then\
+ $(APPLY_PATCHES) $${i%/*} support/libtool as-needed-v1.5.patch; \
+ fi \
+ done
+endef
+
+#
# Hook to patch libtool to make it work properly for cross-compilation
#
define LIBTOOL_PATCH_HOOK
@@ -111,6 +131,17 @@ endef
define inner-autotools-package
+#
+# as-needed is only patched/enabled for target packages
+#
+ifndef $(2)_AS_NEEDED
+ ifeq ($(4),target)
+ $(2)_AS_NEEDED ?= YES
+ else
+ $(2)_AS_NEEDED ?= NO
+ endif
+endif
+
ifndef $(2)_LIBTOOL_PATCH
ifdef $(3)_LIBTOOL_PATCH
$(2)_LIBTOOL_PATCH = $$($(3)_LIBTOOL_PATCH)
@@ -244,6 +275,12 @@ $(2)_PRE_CONFIGURE_HOOKS += AUTORECONF_HOOK
ifneq ($$($(2)_LIBTOOL_PATCH),NO)
$(2)_PRE_CONFIGURE_HOOKS += LIBTOOL_PATCH_HOOK
endif
+# Don't patch packages that skip as-needed
+ifeq ($(BR2_AS_NEEDED),y)
+ifneq ($$($(2)_AS_NEEDED),NO)
+$(2)_PRE_CONFIGURE_HOOKS += LIBTOOL_AS_NEEDED_PATCH_HOOK
+endif
+endif
$(2)_DEPENDENCIES += host-automake host-autoconf host-libtool
else # ! AUTORECONF = YES
@@ -252,6 +289,12 @@ else # ! AUTORECONF = YES
ifneq ($$($(2)_LIBTOOL_PATCH),NO)
$(2)_POST_PATCH_HOOKS += LIBTOOL_PATCH_HOOK
endif
+# Don't patch packages that skip as-needed
+ifeq ($(BR2_AS_NEEDED),y)
+ifneq ($$($(2)_AS_NEEDED),NO)
+$(2)_PRE_CONFIGURE_HOOKS += LIBTOOL_AS_NEEDED_PATCH_HOOK
+endif
+endif
endif
diff --git a/support/libtool/as-needed-v1.5.26.patch b/support/libtool/as-needed-v1.5.26.patch
new file mode 100644
index 0000000..6a347ca
--- /dev/null
+++ b/support/libtool/as-needed-v1.5.26.patch
@@ -0,0 +1,46 @@
+Conveniently fetched from Gentoo, these are basically the same as used
+by Debian.
+https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed
+
+Upstream status: unknown
+
+Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com>
+
+--- a/ltmain.sh.orig 2009-04-18 16:51:52.000000000 +0200
++++ b/ltmain.sh 2009-04-18 16:55:05.000000000 +0200
+@@ -1812,10 +1812,15 @@
+ done
+ IFS="$save_ifs"
+ arg=`$echo "X$arg" | $Xsed -e "s/^ //"`
+ ;;
+
++ -Wl,--as-needed|-Wl,--no-as-needed)
++ deplibs="$deplibs $arg"
++ continue
++ ;;
++
+ -Wl,*)
+ args=`$echo "X$arg" | $Xsed -e "$sed_quote_subst" -e 's/^-Wl,//'`
+ arg=
+ save_ifs="$IFS"; IFS=','
+ for flag in $args; do
+@@ -2152,10 +2157,19 @@
+ fi
+ for deplib in $libs; do
+ lib=
+ found=no
+ case $deplib in
++ -Wl,--as-needed|-Wl,--no-as-needed)
++ if test "$linkmode,$pass" = "prog,link"; then
++ compile_deplibs="$deplib $compile_deplibs"
++ finalize_deplibs="$deplib $finalize_deplibs"
++ else
++ deplibs="$deplib $deplibs"
++ fi
++ continue
++ ;;
+ -mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe|-threads)
+ if test "$linkmode,$pass" = "prog,link"; then
+ compile_deplibs="$deplib $compile_deplibs"
+ finalize_deplibs="$deplib $finalize_deplibs"
+ else
diff --git a/support/libtool/as-needed-v1.5.patch b/support/libtool/as-needed-v1.5.patch
new file mode 100644
index 0000000..15e255c
--- /dev/null
+++ b/support/libtool/as-needed-v1.5.patch
@@ -0,0 +1,38 @@
+Conveniently fetched from Gentoo, these are basically the same as used
+by Debian.
+https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed
+
+Upstream status: unknown
+
+Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com>
+
+--- a/ltmain.sh.orig 2006-03-29 15:45:36.000000000 +0200
++++ b/ltmain.sh 2006-03-29 16:39:30.000000000 +0200
+@@ -1754,6 +1754,11 @@
+ arg=`$echo "X$arg" | $Xsed -e "s/^ //"`
+ ;;
+
++ -Wl,--as-needed|-Wl,--no-as-needed)
++ deplibs="$deplibs $arg"
++ continue
++ ;;
++
+ -Wl,*)
+ args=`$echo "X$arg" | $Xsed -e "$sed_quote_subst" -e 's/^-Wl,//'`
+ arg=
+@@ -2094,6 +2099,15 @@
+ lib=
+ found=no
+ case $deplib in
++ -Wl,--as-needed|-Wl,--no-as-needed)
++ if test "$linkmode,$pass" = "prog,link"; then
++ compile_deplibs="$deplib $compile_deplibs"
++ finalize_deplibs="$deplib $finalize_deplibs"
++ else
++ deplibs="$deplib $deplibs"
++ fi
++ continue
++ ;;
+ -mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe)
+ if test "$linkmode,$pass" = "prog,link"; then
+ compile_deplibs="$deplib $compile_deplibs"
diff --git a/support/libtool/as-needed-v2.2.6.patch b/support/libtool/as-needed-v2.2.6.patch
new file mode 100644
index 0000000..f27c100
--- /dev/null
+++ b/support/libtool/as-needed-v2.2.6.patch
@@ -0,0 +1,46 @@
+Conveniently fetched from Gentoo, these are basically the same as used
+by Debian.
+https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed
+
+Upstream status: unknown
+
+Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com>
+
+--- a/ltmain.sh.orig 2009-04-18 14:37:16.000000000 +0200
++++ b/ltmain.sh 2009-04-18 14:40:08.000000000 +0200
+@@ -4721,10 +4721,15 @@
+ IFS="$save_ifs"
+ func_stripname ' ' '' "$arg"
+ arg=$func_stripname_result
+ ;;
+
++ -Wl,--as-needed|-Wl,--no-as-needed)
++ deplibs="$deplibs $arg"
++ continue
++ ;;
++
+ -Wl,*)
+ func_stripname '-Wl,' '' "$arg"
+ args=$func_stripname_result
+ arg=
+ save_ifs="$IFS"; IFS=','
+@@ -5075,10 +5080,19 @@
+
+ for deplib in $libs; do
+ lib=
+ found=no
+ case $deplib in
++ -Wl,--as-needed|-Wl,--no-as-needed)
++ if test "$linkmode,$pass" = "prog,link"; then
++ compile_deplibs="$deplib $compile_deplibs"
++ finalize_deplibs="$deplib $finalize_deplibs"
++ else
++ deplibs="$deplib $deplibs"
++ fi
++ continue
++ ;;
+ -mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe|-threads)
+ if test "$linkmode,$pass" = "prog,link"; then
+ compile_deplibs="$deplib $compile_deplibs"
+ finalize_deplibs="$deplib $finalize_deplibs"
+ else
diff --git a/support/libtool/as-needed-v2.4.2.patch b/support/libtool/as-needed-v2.4.2.patch
new file mode 100644
index 0000000..0ef0d99
--- /dev/null
+++ b/support/libtool/as-needed-v2.4.2.patch
@@ -0,0 +1,46 @@
+Conveniently fetched from Gentoo, these are basically the same as used
+by Debian.
+https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed
+
+Upstream status: unknown
+
+Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com>
+
+--- a/ltmain.sh.orig 2012-08-19 10:18:57.929178597 +0200
++++ b/ltmain.sh 2012-08-19 10:31:43.409388998 +0200
+@@ -5798,10 +5798,15 @@
+ IFS="$save_ifs"
+ func_stripname ' ' '' "$arg"
+ arg=$func_stripname_result
+ ;;
+
++ -Wl,--as-needed|-Wl,--no-as-needed)
++ deplibs="$deplibs $arg"
++ continue
++ ;;
++
+ -Wl,*)
+ func_stripname '-Wl,' '' "$arg"
+ args=$func_stripname_result
+ arg=
+ save_ifs="$IFS"; IFS=','
+@@ -6158,10 +6163,19 @@
+
+ for deplib in $libs; do
+ lib=
+ found=no
+ case $deplib in
++ -Wl,--as-needed|-Wl,--no-as-needed)
++ if test "$linkmode,$pass" = "prog,link"; then
++ compile_deplibs="$deplib $compile_deplibs"
++ finalize_deplibs="$deplib $finalize_deplibs"
++ else
++ deplibs="$deplib $deplibs"
++ fi
++ continue
++ ;;
+ -mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe \
+ |-threads|-fopenmp|-openmp|-mp|-xopenmp|-omp|-qsmp=*)
+ if test "$linkmode,$pass" = "prog,link"; then
+ compile_deplibs="$deplib $compile_deplibs"
+ finalize_deplibs="$deplib $finalize_deplibs"
diff --git a/support/libtool/as-needed-v2.4.3.patch b/support/libtool/as-needed-v2.4.3.patch
new file mode 100644
index 0000000..25e6dfc
--- /dev/null
+++ b/support/libtool/as-needed-v2.4.3.patch
@@ -0,0 +1,46 @@
+Conveniently fetched from Gentoo, these are basically the same as used
+by Debian.
+https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed
+
+Upstream status: unknown
+
+Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com>
+
+--- a/ltmain.sh
++++ b/ltmain.sh
+@@ -7225,10 +7225,15 @@
+ IFS=$save_ifs
+ func_stripname ' ' '' "$arg"
+ arg=$func_stripname_result
+ ;;
+
++ -Wl,--as-needed|-Wl,--no-as-needed)
++ deplibs="$deplibs $arg"
++ continue
++ ;;
++
+ -Wl,*)
+ func_stripname '-Wl,' '' "$arg"
+ args=$func_stripname_result
+ arg=
+ save_ifs=$IFS; IFS=,
+@@ -7609,10 +7614,19 @@
+
+ for deplib in $libs; do
+ lib=
+ found=false
+ case $deplib in
++ -Wl,--as-needed|-Wl,--no-as-needed)
++ if test "$linkmode,$pass" = "prog,link"; then
++ compile_deplibs="$deplib $compile_deplibs"
++ finalize_deplibs="$deplib $finalize_deplibs"
++ else
++ deplibs="$deplib $deplibs"
++ fi
++ continue
++ ;;
+ -mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe \
+ |-threads|-fopenmp|-openmp|-mp|-xopenmp|-omp|-qsmp=*)
+ if test prog,link = "$linkmode,$pass"; then
+ compile_deplibs="$deplib $compile_deplibs"
+ finalize_deplibs="$deplib $finalize_deplibs"
--
2.7.3
^ permalink raw reply related [flat|nested] 6+ messages in thread* [Buildroot] [PATCH 2/2] docs/manual: document PKG_AS_NEEDED 2016-07-17 15:05 [Buildroot] [PATCH 1/2] build: add support for as-needed linking gustavo.zacarias at free-electrons.com @ 2016-07-17 15:05 ` gustavo.zacarias at free-electrons.com 2016-07-17 21:01 ` [Buildroot] [PATCH 1/2] build: add support for as-needed linking Yann E. MORIN 2016-09-20 18:07 ` Thomas Petazzoni 2 siblings, 0 replies; 6+ messages in thread From: gustavo.zacarias at free-electrons.com @ 2016-07-17 15:05 UTC (permalink / raw) To: buildroot From: Gustavo Zacarias <gustavo.zacarias@free-electrons.com> Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com> --- docs/manual/adding-packages-autotools.txt | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/docs/manual/adding-packages-autotools.txt b/docs/manual/adding-packages-autotools.txt index a041d91..e37e1e0 100644 --- a/docs/manual/adding-packages-autotools.txt +++ b/docs/manual/adding-packages-autotools.txt @@ -147,6 +147,10 @@ cases, typical packages will therefore only use a few of them. not. Valid values are +YES+ and +NO+. By default, the value is +YES+ +* +LIBFOO_AS_NEEDED+ tells wether as-needed linking should be enabled + or disabled. Valid values are +YES+ and +NO+. By default, the + value is +YES+ + * +LIBFOO_INSTALL_STAGING_OPTS+ contains the make options used to install the package to the staging directory. By default, the value is +DESTDIR=$(STAGING_DIR) install+, which is -- 2.7.3 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* [Buildroot] [PATCH 1/2] build: add support for as-needed linking 2016-07-17 15:05 [Buildroot] [PATCH 1/2] build: add support for as-needed linking gustavo.zacarias at free-electrons.com 2016-07-17 15:05 ` [Buildroot] [PATCH 2/2] docs/manual: document PKG_AS_NEEDED gustavo.zacarias at free-electrons.com @ 2016-07-17 21:01 ` Yann E. MORIN 2016-07-18 0:36 ` Gustavo Zacarias 2016-09-20 18:07 ` Thomas Petazzoni 2 siblings, 1 reply; 6+ messages in thread From: Yann E. MORIN @ 2016-07-17 21:01 UTC (permalink / raw) To: buildroot Gustavo, All, On 2016-07-17 12:05 -0300, gustavo.zacarias at free-electrons.com spake thusly: > From: Gustavo Zacarias <gustavo.zacarias@free-electrons.com> > > This option tells the linker to only link to the libraries containing > symbols that are actually used. > > It requires libtool patches to fully clean the needed chain, these are > used by major distributions such as Debian and Gentoo. > https://wiki.debian.org/ToolChain/DSOLinking > https://wiki.gentoo.org/wiki/Project:Quality_Assurance/As-needed OK, I read both of the above, and I do understand the technicalities behind --as-needed. However, I fail to see what it would bring to Buidlroot. One key point of --as-needed is to not pull in an unneeded library into an executable, in case it does not need it, especially in the case that this library is a second-order depedency by way of another library, e.g.: foo: NEEDED: libbar.so NEEDED: libbuz.so libbar.so: NEEDED: libbuz.so but where foo does not use any symbol from libbuz.so. This purportedly allows to update second-order libraries (libbuz, above) when there is an ABI change in those libs, and only have to rebuild first-order libs (libbar, above) without to rebuild the executable itself. Another key point is that the dynamic loader will not have to load unncessary libraries,thus reducing startup time. However, I fail to see how that can be any usefull in the context of Buildroot. First, we do not support partial updates, and only catter to full-system updates. Thus the first point is moot IMHO. Second, the default behaviour of the dynamic linker is to do lazy binding, i.e. to only resolve sumbols at the time they are first needed, and thus only loading libraries to resolve a missing symbol (unless I'm mistaken...) So, what would that bring to us? Regards, Yann E. MORIN. > Introduce a BR2_AS_NEEDED global enable option (default=no, marked as > experimental) that generally disables the libtool patching and avoids > the extra LDFLAGS (-Wl,--as-needed). > > Also add a per-package PACKAGE_AS_NEEDED (default=yes) option to work > around problematic packages that might not behave too well with > as-needed linking. > > For the libtool patching use a guess (automatic) method since > version-matching doesn't work accurately with some packages that ship > patched/modified ltmain.sh scripts, normally based on 2.4. In some of > these cases the as-needed-v2.2.6.patch works, and in other cases the > as-needed-v2.4.2.patch is necessary and the exact condition can't be > found in a deterministic way. If for some reason none of the patches > applies to a particular package this will only affect said package and > shouldn't have any consequence even if passing -Wl,--as-needed LDFLAGS. > > Example for a simple defconfig: > BR2_arm=y > BR2_AS_NEEDED=y > BR2_TOOLCHAIN_EXTERNAL=y > BR2_PACKAGE_GSTREAMER1=y > BR2_PACKAGE_GST1_PLUGINS_BAD=y > > With as-needed disabled: > $ readelf -a libgstbadvideo-1.0.so|grep "(NEEDED)"|wc -l > 10 > > With as-needed enabled: > $ readelf -a libgstbadvideo-1.0.so|grep "(NEEDED)"|wc -l > 8 > > Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com> > --- > Config.in | 6 +++++ > package/Makefile.in | 5 ++++ > package/pkg-autotools.mk | 43 ++++++++++++++++++++++++++++++ > support/libtool/as-needed-v1.5.26.patch | 46 +++++++++++++++++++++++++++++++++ > support/libtool/as-needed-v1.5.patch | 38 +++++++++++++++++++++++++++ > support/libtool/as-needed-v2.2.6.patch | 46 +++++++++++++++++++++++++++++++++ > support/libtool/as-needed-v2.4.2.patch | 46 +++++++++++++++++++++++++++++++++ > support/libtool/as-needed-v2.4.3.patch | 46 +++++++++++++++++++++++++++++++++ > 8 files changed, 276 insertions(+) > create mode 100644 support/libtool/as-needed-v1.5.26.patch > create mode 100644 support/libtool/as-needed-v1.5.patch > create mode 100644 support/libtool/as-needed-v2.2.6.patch > create mode 100644 support/libtool/as-needed-v2.4.2.patch > create mode 100644 support/libtool/as-needed-v2.4.3.patch > > diff --git a/Config.in b/Config.in > index 7bb2a01..e8b0477 100644 > --- a/Config.in > +++ b/Config.in > @@ -739,6 +739,12 @@ config BR2_REPRODUCIBLE > This is labeled as an experimental feature, as not all > packages behave properly to ensure reproducibility. > > +config BR2_AS_NEEDED > + bool "Link target binaries/libraries as-needed (experimental)" > + help > + Tell the linker to link in the produced binary/library only > + the libraries containing symbols that are actually used. > + > endmenu > > source "toolchain/Config.in" > diff --git a/package/Makefile.in b/package/Makefile.in > index afd5d3a..b190363 100644 > --- a/package/Makefile.in > +++ b/package/Makefile.in > @@ -144,6 +144,11 @@ TARGET_CXXFLAGS = $(TARGET_CFLAGS) > TARGET_FCFLAGS = $(TARGET_ABI) $(TARGET_OPTIMIZATION) $(TARGET_DEBUGGING) > TARGET_LDFLAGS = $(call qstrip,$(BR2_TARGET_LDFLAGS)) > > +# $(PKG)_AS_NEEDED gets expanded too early for ifeq usage, so use subst instead > +ifeq ($(BR2_AS_NEEDED),y) > +TARGET_LDFLAGS += -Wl,$(subst NO,--no,$(subst YES,-,$($(PKG)_AS_NEEDED)))-as-needed > +endif > + > ifeq ($(BR2_BINFMT_FLAT),y) > TARGET_CFLAGS += $(if $($(PKG)_FLAT_STACKSIZE),-Wl$(comma)-elf2flt=-s$($(PKG)_FLAT_STACKSIZE),\ > -Wl$(comma)-elf2flt) > diff --git a/package/pkg-autotools.mk b/package/pkg-autotools.mk > index 75e2df0..de00628 100644 > --- a/package/pkg-autotools.mk > +++ b/package/pkg-autotools.mk > @@ -55,6 +55,26 @@ define UPDATE_CONFIG_HOOK > endef > > # > +# Hook to patch libtool to make it work properly for as-needed linking > +# > +define LIBTOOL_AS_NEEDED_PATCH_HOOK > + @$(call MESSAGE,"Patching libtool as-needed") > + $(Q)for i in `find $($(PKG)_SRCDIR) -name ltmain.sh`; do \ > + if patch -p1 --dry-run -f -s -d $${i%/*} <support/libtool/as-needed-v2.4.3.patch >/dev/null ; then\ > + $(APPLY_PATCHES) $${i%/*} support/libtool as-needed-v2.4.3.patch; \ > + elif patch -p1 --dry-run -f -s -d $${i%/*} <support/libtool/as-needed-v2.4.2.patch >/dev/null ; then\ > + $(APPLY_PATCHES) $${i%/*} support/libtool as-needed-v2.4.2.patch; \ > + elif patch -p1 --dry-run -f -s -d $${i%/*} <support/libtool/as-needed-v2.2.6.patch >/dev/null ; then\ > + $(APPLY_PATCHES) $${i%/*} support/libtool as-needed-v2.2.6.patch; \ > + elif patch -p1 --dry-run -f -s -d $${i%/*} <support/libtool/as-needed-v1.5.26.patch >/dev/null ; then\ > + $(APPLY_PATCHES) $${i%/*} support/libtool as-needed-v1.5.26.patch; \ > + elif patch -p1 --dry-run -f -s -d $${i%/*} <support/libtool/as-needed-v1.5.patch >/dev/null ; then\ > + $(APPLY_PATCHES) $${i%/*} support/libtool as-needed-v1.5.patch; \ > + fi \ > + done > +endef > + > +# > # Hook to patch libtool to make it work properly for cross-compilation > # > define LIBTOOL_PATCH_HOOK > @@ -111,6 +131,17 @@ endef > > define inner-autotools-package > > +# > +# as-needed is only patched/enabled for target packages > +# > +ifndef $(2)_AS_NEEDED > + ifeq ($(4),target) > + $(2)_AS_NEEDED ?= YES > + else > + $(2)_AS_NEEDED ?= NO > + endif > +endif > + > ifndef $(2)_LIBTOOL_PATCH > ifdef $(3)_LIBTOOL_PATCH > $(2)_LIBTOOL_PATCH = $$($(3)_LIBTOOL_PATCH) > @@ -244,6 +275,12 @@ $(2)_PRE_CONFIGURE_HOOKS += AUTORECONF_HOOK > ifneq ($$($(2)_LIBTOOL_PATCH),NO) > $(2)_PRE_CONFIGURE_HOOKS += LIBTOOL_PATCH_HOOK > endif > +# Don't patch packages that skip as-needed > +ifeq ($(BR2_AS_NEEDED),y) > +ifneq ($$($(2)_AS_NEEDED),NO) > +$(2)_PRE_CONFIGURE_HOOKS += LIBTOOL_AS_NEEDED_PATCH_HOOK > +endif > +endif > $(2)_DEPENDENCIES += host-automake host-autoconf host-libtool > > else # ! AUTORECONF = YES > @@ -252,6 +289,12 @@ else # ! AUTORECONF = YES > ifneq ($$($(2)_LIBTOOL_PATCH),NO) > $(2)_POST_PATCH_HOOKS += LIBTOOL_PATCH_HOOK > endif > +# Don't patch packages that skip as-needed > +ifeq ($(BR2_AS_NEEDED),y) > +ifneq ($$($(2)_AS_NEEDED),NO) > +$(2)_PRE_CONFIGURE_HOOKS += LIBTOOL_AS_NEEDED_PATCH_HOOK > +endif > +endif > > endif > > diff --git a/support/libtool/as-needed-v1.5.26.patch b/support/libtool/as-needed-v1.5.26.patch > new file mode 100644 > index 0000000..6a347ca > --- /dev/null > +++ b/support/libtool/as-needed-v1.5.26.patch > @@ -0,0 +1,46 @@ > +Conveniently fetched from Gentoo, these are basically the same as used > +by Debian. > +https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed > + > +Upstream status: unknown > + > +Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com> > + > +--- a/ltmain.sh.orig 2009-04-18 16:51:52.000000000 +0200 > ++++ b/ltmain.sh 2009-04-18 16:55:05.000000000 +0200 > +@@ -1812,10 +1812,15 @@ > + done > + IFS="$save_ifs" > + arg=`$echo "X$arg" | $Xsed -e "s/^ //"` > + ;; > + > ++ -Wl,--as-needed|-Wl,--no-as-needed) > ++ deplibs="$deplibs $arg" > ++ continue > ++ ;; > ++ > + -Wl,*) > + args=`$echo "X$arg" | $Xsed -e "$sed_quote_subst" -e 's/^-Wl,//'` > + arg= > + save_ifs="$IFS"; IFS=',' > + for flag in $args; do > +@@ -2152,10 +2157,19 @@ > + fi > + for deplib in $libs; do > + lib= > + found=no > + case $deplib in > ++ -Wl,--as-needed|-Wl,--no-as-needed) > ++ if test "$linkmode,$pass" = "prog,link"; then > ++ compile_deplibs="$deplib $compile_deplibs" > ++ finalize_deplibs="$deplib $finalize_deplibs" > ++ else > ++ deplibs="$deplib $deplibs" > ++ fi > ++ continue > ++ ;; > + -mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe|-threads) > + if test "$linkmode,$pass" = "prog,link"; then > + compile_deplibs="$deplib $compile_deplibs" > + finalize_deplibs="$deplib $finalize_deplibs" > + else > diff --git a/support/libtool/as-needed-v1.5.patch b/support/libtool/as-needed-v1.5.patch > new file mode 100644 > index 0000000..15e255c > --- /dev/null > +++ b/support/libtool/as-needed-v1.5.patch > @@ -0,0 +1,38 @@ > +Conveniently fetched from Gentoo, these are basically the same as used > +by Debian. > +https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed > + > +Upstream status: unknown > + > +Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com> > + > +--- a/ltmain.sh.orig 2006-03-29 15:45:36.000000000 +0200 > ++++ b/ltmain.sh 2006-03-29 16:39:30.000000000 +0200 > +@@ -1754,6 +1754,11 @@ > + arg=`$echo "X$arg" | $Xsed -e "s/^ //"` > + ;; > + > ++ -Wl,--as-needed|-Wl,--no-as-needed) > ++ deplibs="$deplibs $arg" > ++ continue > ++ ;; > ++ > + -Wl,*) > + args=`$echo "X$arg" | $Xsed -e "$sed_quote_subst" -e 's/^-Wl,//'` > + arg= > +@@ -2094,6 +2099,15 @@ > + lib= > + found=no > + case $deplib in > ++ -Wl,--as-needed|-Wl,--no-as-needed) > ++ if test "$linkmode,$pass" = "prog,link"; then > ++ compile_deplibs="$deplib $compile_deplibs" > ++ finalize_deplibs="$deplib $finalize_deplibs" > ++ else > ++ deplibs="$deplib $deplibs" > ++ fi > ++ continue > ++ ;; > + -mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe) > + if test "$linkmode,$pass" = "prog,link"; then > + compile_deplibs="$deplib $compile_deplibs" > diff --git a/support/libtool/as-needed-v2.2.6.patch b/support/libtool/as-needed-v2.2.6.patch > new file mode 100644 > index 0000000..f27c100 > --- /dev/null > +++ b/support/libtool/as-needed-v2.2.6.patch > @@ -0,0 +1,46 @@ > +Conveniently fetched from Gentoo, these are basically the same as used > +by Debian. > +https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed > + > +Upstream status: unknown > + > +Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com> > + > +--- a/ltmain.sh.orig 2009-04-18 14:37:16.000000000 +0200 > ++++ b/ltmain.sh 2009-04-18 14:40:08.000000000 +0200 > +@@ -4721,10 +4721,15 @@ > + IFS="$save_ifs" > + func_stripname ' ' '' "$arg" > + arg=$func_stripname_result > + ;; > + > ++ -Wl,--as-needed|-Wl,--no-as-needed) > ++ deplibs="$deplibs $arg" > ++ continue > ++ ;; > ++ > + -Wl,*) > + func_stripname '-Wl,' '' "$arg" > + args=$func_stripname_result > + arg= > + save_ifs="$IFS"; IFS=',' > +@@ -5075,10 +5080,19 @@ > + > + for deplib in $libs; do > + lib= > + found=no > + case $deplib in > ++ -Wl,--as-needed|-Wl,--no-as-needed) > ++ if test "$linkmode,$pass" = "prog,link"; then > ++ compile_deplibs="$deplib $compile_deplibs" > ++ finalize_deplibs="$deplib $finalize_deplibs" > ++ else > ++ deplibs="$deplib $deplibs" > ++ fi > ++ continue > ++ ;; > + -mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe|-threads) > + if test "$linkmode,$pass" = "prog,link"; then > + compile_deplibs="$deplib $compile_deplibs" > + finalize_deplibs="$deplib $finalize_deplibs" > + else > diff --git a/support/libtool/as-needed-v2.4.2.patch b/support/libtool/as-needed-v2.4.2.patch > new file mode 100644 > index 0000000..0ef0d99 > --- /dev/null > +++ b/support/libtool/as-needed-v2.4.2.patch > @@ -0,0 +1,46 @@ > +Conveniently fetched from Gentoo, these are basically the same as used > +by Debian. > +https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed > + > +Upstream status: unknown > + > +Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com> > + > +--- a/ltmain.sh.orig 2012-08-19 10:18:57.929178597 +0200 > ++++ b/ltmain.sh 2012-08-19 10:31:43.409388998 +0200 > +@@ -5798,10 +5798,15 @@ > + IFS="$save_ifs" > + func_stripname ' ' '' "$arg" > + arg=$func_stripname_result > + ;; > + > ++ -Wl,--as-needed|-Wl,--no-as-needed) > ++ deplibs="$deplibs $arg" > ++ continue > ++ ;; > ++ > + -Wl,*) > + func_stripname '-Wl,' '' "$arg" > + args=$func_stripname_result > + arg= > + save_ifs="$IFS"; IFS=',' > +@@ -6158,10 +6163,19 @@ > + > + for deplib in $libs; do > + lib= > + found=no > + case $deplib in > ++ -Wl,--as-needed|-Wl,--no-as-needed) > ++ if test "$linkmode,$pass" = "prog,link"; then > ++ compile_deplibs="$deplib $compile_deplibs" > ++ finalize_deplibs="$deplib $finalize_deplibs" > ++ else > ++ deplibs="$deplib $deplibs" > ++ fi > ++ continue > ++ ;; > + -mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe \ > + |-threads|-fopenmp|-openmp|-mp|-xopenmp|-omp|-qsmp=*) > + if test "$linkmode,$pass" = "prog,link"; then > + compile_deplibs="$deplib $compile_deplibs" > + finalize_deplibs="$deplib $finalize_deplibs" > diff --git a/support/libtool/as-needed-v2.4.3.patch b/support/libtool/as-needed-v2.4.3.patch > new file mode 100644 > index 0000000..25e6dfc > --- /dev/null > +++ b/support/libtool/as-needed-v2.4.3.patch > @@ -0,0 +1,46 @@ > +Conveniently fetched from Gentoo, these are basically the same as used > +by Debian. > +https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed > + > +Upstream status: unknown > + > +Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com> > + > +--- a/ltmain.sh > ++++ b/ltmain.sh > +@@ -7225,10 +7225,15 @@ > + IFS=$save_ifs > + func_stripname ' ' '' "$arg" > + arg=$func_stripname_result > + ;; > + > ++ -Wl,--as-needed|-Wl,--no-as-needed) > ++ deplibs="$deplibs $arg" > ++ continue > ++ ;; > ++ > + -Wl,*) > + func_stripname '-Wl,' '' "$arg" > + args=$func_stripname_result > + arg= > + save_ifs=$IFS; IFS=, > +@@ -7609,10 +7614,19 @@ > + > + for deplib in $libs; do > + lib= > + found=false > + case $deplib in > ++ -Wl,--as-needed|-Wl,--no-as-needed) > ++ if test "$linkmode,$pass" = "prog,link"; then > ++ compile_deplibs="$deplib $compile_deplibs" > ++ finalize_deplibs="$deplib $finalize_deplibs" > ++ else > ++ deplibs="$deplib $deplibs" > ++ fi > ++ continue > ++ ;; > + -mt|-mthreads|-kthread|-Kthread|-pthread|-pthreads|--thread-safe \ > + |-threads|-fopenmp|-openmp|-mp|-xopenmp|-omp|-qsmp=*) > + if test prog,link = "$linkmode,$pass"; then > + compile_deplibs="$deplib $compile_deplibs" > + finalize_deplibs="$deplib $finalize_deplibs" > -- > 2.7.3 > > _______________________________________________ > buildroot mailing list > buildroot at busybox.net > http://lists.busybox.net/mailman/listinfo/buildroot -- .-----------------.--------------------.------------------.--------------------. | Yann E. MORIN | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: | | +33 662 376 056 | Software Designer | \ / CAMPAIGN | ___ | | +33 223 225 172 `------------.-------: X AGAINST | \e/ There is no | | http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL | v conspiracy. | '------------------------------^-------^------------------^--------------------' ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Buildroot] [PATCH 1/2] build: add support for as-needed linking 2016-07-17 21:01 ` [Buildroot] [PATCH 1/2] build: add support for as-needed linking Yann E. MORIN @ 2016-07-18 0:36 ` Gustavo Zacarias 2016-09-20 23:17 ` Peter Korsgaard 0 siblings, 1 reply; 6+ messages in thread From: Gustavo Zacarias @ 2016-07-18 0:36 UTC (permalink / raw) To: buildroot On 17/07/16 18:01, Yann E. MORIN wrote: > OK, I read both of the above, and I do understand the technicalities > behind --as-needed. > > However, I fail to see what it would bring to Buidlroot. > > One key point of --as-needed is to not pull in an unneeded library into > an executable, in case it does not need it, especially in the case that > this library is a second-order depedency by way of another library, > e.g.: > > foo: > NEEDED: libbar.so > NEEDED: libbuz.so > > libbar.so: > NEEDED: libbuz.so > > but where foo does not use any symbol from libbuz.so. This purportedly > allows to update second-order libraries (libbuz, above) when there is > an ABI change in those libs, and only have to rebuild first-order libs > (libbar, above) without to rebuild the executable itself. Hi Yann. Indeed this is not the point of the new option. > Another key point is that the dynamic loader will not have to load > unncessary libraries,thus reducing startup time. But this is. > However, I fail to see how that can be any usefull in the context of > Buildroot. > > First, we do not support partial updates, and only catter to full-system > updates. Thus the first point is moot IMHO. Agreed. > Second, the default behaviour of the dynamic linker is to do lazy > binding, i.e. to only resolve sumbols at the time they are first needed, > and thus only loading libraries to resolve a missing symbol (unless I'm > mistaken...) > > > So, what would that bring to us? Yes, that's what lazy binding does... but it's still based on DT_NEEDED entries, hence instead of scanning 10 libraries at required time in my example it will only need to scan 8 to resolve required symbols. For more complex applications that use many nested libraries the savings can be bigger. Example diff between non-as-needed gst-launch-1.0 and as-needed version: libgstreamer-1.0.so.0 libgobject-2.0.so.0 -libgmodule-2.0.so.0 libglib-2.0.so.0 -librt.so.1 -libdl.so.2 libgcc_s.so.1 libpthread.so.0 libc.so.6 Most of the time even with lazy bindings any given binary will need to resolve symbols unless we are building statically. Regards. ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Buildroot] [PATCH 1/2] build: add support for as-needed linking 2016-07-18 0:36 ` Gustavo Zacarias @ 2016-09-20 23:17 ` Peter Korsgaard 0 siblings, 0 replies; 6+ messages in thread From: Peter Korsgaard @ 2016-09-20 23:17 UTC (permalink / raw) To: buildroot >>>>> "Gustavo" == Gustavo Zacarias <gustavo.zacarias@free-electrons.com> writes: Hi, >> So, what would that bring to us? > Yes, that's what lazy binding does... but it's still based on > DT_NEEDED entries, hence instead of scanning 10 libraries at required > time in my example it will only need to scan 8 to resolve required > symbols. > For more complex applications that use many nested libraries the > savings can be bigger. > Example diff between non-as-needed gst-launch-1.0 and as-needed version: > libgstreamer-1.0.so.0 > libgobject-2.0.so.0 > -libgmodule-2.0.so.0 > libglib-2.0.so.0 > -librt.so.1 > -libdl.so.2 > libgcc_s.so.1 > libpthread.so.0 > libc.so.6 So what is E.G. the time differences when running time gst-launch-1.0 fakesrc num-buffers=1 ! fakesink on a "normal" machine with/without these patches? (Notice that gstreamer searches plugins and creates cache file first time it is run). -- Bye, Peter Korsgaard ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Buildroot] [PATCH 1/2] build: add support for as-needed linking 2016-07-17 15:05 [Buildroot] [PATCH 1/2] build: add support for as-needed linking gustavo.zacarias at free-electrons.com 2016-07-17 15:05 ` [Buildroot] [PATCH 2/2] docs/manual: document PKG_AS_NEEDED gustavo.zacarias at free-electrons.com 2016-07-17 21:01 ` [Buildroot] [PATCH 1/2] build: add support for as-needed linking Yann E. MORIN @ 2016-09-20 18:07 ` Thomas Petazzoni 2 siblings, 0 replies; 6+ messages in thread From: Thomas Petazzoni @ 2016-09-20 18:07 UTC (permalink / raw) To: buildroot Hello, On Sun, 17 Jul 2016 12:05:57 -0300, gustavo.zacarias at free-electrons.com wrote: > From: Gustavo Zacarias <gustavo.zacarias@free-electrons.com> > > This option tells the linker to only link to the libraries containing > symbols that are actually used. > > It requires libtool patches to fully clean the needed chain, these are > used by major distributions such as Debian and Gentoo. > https://wiki.debian.org/ToolChain/DSOLinking > https://wiki.gentoo.org/wiki/Project:Quality_Assurance/As-needed > > Introduce a BR2_AS_NEEDED global enable option (default=no, marked as > experimental) that generally disables the libtool patching and avoids > the extra LDFLAGS (-Wl,--as-needed). > > Also add a per-package PACKAGE_AS_NEEDED (default=yes) option to work > around problematic packages that might not behave too well with > as-needed linking. > > For the libtool patching use a guess (automatic) method since > version-matching doesn't work accurately with some packages that ship > patched/modified ltmain.sh scripts, normally based on 2.4. In some of > these cases the as-needed-v2.2.6.patch works, and in other cases the > as-needed-v2.4.2.patch is necessary and the exact condition can't be > found in a deterministic way. If for some reason none of the patches > applies to a particular package this will only affect said package and > shouldn't have any consequence even if passing -Wl,--as-needed LDFLAGS. Just like Yann, I don't understand the usefulness of --as-needed support. If a library A is not using symbols from a library B it is linked against, why is library A linked against library B in the first place ? The way you present it makes me understand that --as-needed is a workaround for broken package build systems, which end up producing binaries (programs or libraries) incorrect linked to too many libraries, that are in fact not all needed. In addition to this, it is not really clear what are the benefits of having less NEEDED entries (i.e practical number of performance improvements). Since the complexity is quite huge for something that 1/ looks like a workaround and 2/ isn't associated to concrete performance improvements, I don't think we want to merge this at this point. Of course, feel free to come back with some more details on why --as-needed is useful (why it's not a workaround, and prove it's really useful in practice). Thanks a lot, Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-09-20 23:17 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2016-07-17 15:05 [Buildroot] [PATCH 1/2] build: add support for as-needed linking gustavo.zacarias at free-electrons.com 2016-07-17 15:05 ` [Buildroot] [PATCH 2/2] docs/manual: document PKG_AS_NEEDED gustavo.zacarias at free-electrons.com 2016-07-17 21:01 ` [Buildroot] [PATCH 1/2] build: add support for as-needed linking Yann E. MORIN 2016-07-18 0:36 ` Gustavo Zacarias 2016-09-20 23:17 ` Peter Korsgaard 2016-09-20 18:07 ` Thomas Petazzoni
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