[Buildroot] [PATCH 1/1] elfutils: Add a --{enable, disable}-backends option

[Buildroot] [PATCH 1/1] elfutils: Add a --{enable, disable}-backends option

[Jan Heylen]

Add a --{enable,disable}-backends configuration option to elfutils. This
allows to selectively disable the compilation of the libebl backends
shared libraries. This is usefull when some application require linking
against the elfutils libelf, but don't require the backends to be available
on target.

Signed-off-by: Jan Heylen <heyleke@gmail.com>
---
 package/elfutils/0007-backends-configurable.patch | 44 +++++++++++++++++++++++
 package/elfutils/Config.in                        | 13 +++++++
 package/elfutils/elfutils.mk                      |  6 ++++
 3 files changed, 63 insertions(+)
 create mode 100644 package/elfutils/0007-backends-configurable.patch

diff --git a/package/elfutils/0007-backends-configurable.patch b/package/elfutils/0007-backends-configurable.patch
new file mode 100644
index 0000000..b93e2da
--- /dev/null
+++ b/package/elfutils/0007-backends-configurable.patch
@@ -0,0 +1,44 @@
+Index: elfutils-0.161/Makefile.am
+===================================================================
+--- elfutils-0.161.orig/Makefile.am	2015-04-01 19:56:35.090112704 +0200
++++ elfutils-0.161/Makefile.am	2015-04-01 19:59:19.688605184 +0200
+@@ -22,13 +22,18 @@
+ 
+ pkginclude_HEADERS = version.h
+ 
++# Add doc back when we have some real content.
++SUBDIRS = config m4 lib libelf libebl libdwel flibdwfl libdw libcpu libasm
++
++if ENABLE_BACKENDS
++  SUBDIRS += backends
++endif
++
+ if ENABLE_PROGS
+-PROGS_SUBDIR = src
++  SUBDIRS += src
+ endif
+ 
+-# Add doc back when we have some real content.
+-SUBDIRS = config m4 lib libelf libebl libdwelf libdwfl libdw libcpu libasm \
+-	  backends $(PROGS_SUBDIR) tests
++SUBDIRS += tests
+ 
+ EXTRA_DIST = elfutils.spec GPG-KEY NOTES CONTRIBUTING \
+ 	     COPYING COPYING-GPLV2 COPYING-LGPLV3
+Index: elfutils-0.161/configure.ac
+===================================================================
+--- elfutils-0.161.orig/configure.ac	2015-04-01 19:56:35.090112704 +0200
++++ elfutils-0.161/configure.ac	2015-04-01 19:56:35.086112308 +0200
+@@ -253,6 +253,12 @@
+ AC_DEFINE_UNQUOTED(LIBEBL_SUBDIR, "$LIBEBL_SUBDIR")
+ AH_TEMPLATE([LIBEBL_SUBDIR], [$libdir subdirectory containing libebl modules.])
+ 
++AC_ARG_ENABLE([backends],
++	AS_HELP_STRING([--enable-backends], [enable backends]),
++	enable_backends=$enableval,
++	enable_backends=yes)
++AM_CONDITIONAL(ENABLE_BACKENDS, test "$enable_backends" = yes)
++
+ AC_CHECK_FUNC([argp_parse])
+ if test "$ac_cv_func_argp_parse" != yes; then
+ 	AC_CHECK_LIB([argp],[argp_parse],ARGP_LIBS=-largp,
diff --git a/package/elfutils/Config.in b/package/elfutils/Config.in
index cb9a658..fc85013 100644
--- a/package/elfutils/Config.in
+++ b/package/elfutils/Config.in
@@ -30,4 +30,17 @@ config BR2_PACKAGE_ELFUTILS_PROGS
 	  This option tells elfutils to not only install the libelf
 	  libraries, but also the elfutils programs.
 
+config BR2_PACKAGE_ELFUTILS_BACKENDS
+	bool "Build and install backend shared libraries"
+	default y
+	help
+	  This option tells elfutils to not only install the libelf
+	  libraries, but also the libebl backend shared libraries
+	  with architecture specific code to read elf files. If you
+	  intend to use libelf/libebl at-runtime, say 'y' here.
+	  If you only need to link against libelf at-compile-time,
+	  but not really using it, you can leave the architecture
+	  specific backends uninstalled. Loading of the backend library
+	  by libebl will fail in that case.
+
 endif
diff --git a/package/elfutils/elfutils.mk b/package/elfutils/elfutils.mk
index 9901bcb..8b2cfd8 100644
--- a/package/elfutils/elfutils.mk
+++ b/package/elfutils/elfutils.mk
@@ -65,4 +65,10 @@ else
 ELFUTILS_CONF_OPTS += --disable-progs
 endif
 
+ifeq ($(BR2_PACKAGE_ELFUTILS_BACKENDS),y)
+ ELFUTILS_CONF_OPTS += --enable-backends
+else
+ ELFUTILS_CONF_OPTS += --disable-backends
+endif
+
 $(eval $(autotools-package))
-- 
1.9.1

[Buildroot] [PATCH 1/1] elfutils: Add a --{enable, disable}-backends option

[Thomas Petazzoni]

Dear Jan Heylen,

On Wed,  1 Apr 2015 20:12:05 +0200, Jan Heylen wrote:

> diff --git a/package/elfutils/0007-backends-configurable.patch b/package/elfutils/0007-backends-configurable.patch
> new file mode 100644
> index 0000000..b93e2da
> --- /dev/null
> +++ b/package/elfutils/0007-backends-configurable.patch

Patches should have a description and a Signed-off-by line.

Also, could you submit this patch upstream? I'd like to see if upstream
is willing to accept such a patch, since it is more or less a "feature"
patch, and we prefer to not have to carry such patches forever.

> +config BR2_PACKAGE_ELFUTILS_BACKENDS
> +	bool "Build and install backend shared libraries"
> +	default y
> +	help
> +	  This option tells elfutils to not only install the libelf
> +	  libraries, but also the libebl backend shared libraries
> +	  with architecture specific code to read elf files. If you
> +	  intend to use libelf/libebl at-runtime, say 'y' here.
> +	  If you only need to link against libelf at-compile-time,
> +	  but not really using it, you can leave the architecture
> +	  specific backends uninstalled. Loading of the backend library
> +	  by libebl will fail in that case.

This explanation seems weird: why would you link against libelf and not
use it?

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] [PATCH 1/1] elfutils: Add a --{enable, disable}-backends option

[Jan Heylen]

On Wed, Apr 1, 2015 at 9:43 PM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Dear Jan Heylen,
>
> On Wed,  1 Apr 2015 20:12:05 +0200, Jan Heylen wrote:
>
>> diff --git a/package/elfutils/0007-backends-configurable.patch b/package/elfutils/0007-backends-configurable.patch
>> new file mode 100644
>> index 0000000..b93e2da
>> --- /dev/null
>> +++ b/package/elfutils/0007-backends-configurable.patch
>
> Patches should have a description and a Signed-off-by line.
Ah, I didn`t realise that on that level it was required, I'll fix it

>
> Also, could you submit this patch upstream? I'd like to see if upstream
> is willing to accept such a patch, since it is more or less a "feature"
> patch, and we prefer to not have to carry such patches forever.
This is based on 0002-disable-progs.patch, so it belongs in buildroot?
I'll try to upstream it to the elfutils package.

>
>> +config BR2_PACKAGE_ELFUTILS_BACKENDS
>> +     bool "Build and install backend shared libraries"
>> +     default y
>> +     help
>> +       This option tells elfutils to not only install the libelf
>> +       libraries, but also the libebl backend shared libraries
>> +       with architecture specific code to read elf files. If you
>> +       intend to use libelf/libebl at-runtime, say 'y' here.
>> +       If you only need to link against libelf at-compile-time,
>> +       but not really using it, you can leave the architecture
>> +       specific backends uninstalled. Loading of the backend library
>> +       by libebl will fail in that case.
>
> This explanation seems weird: why would you link against libelf and not
> use it?

The backends are plaform specific implementations, for every supported
platform. And, e.g. perf package which sources come with the Linux
kernel has a compile time dependency on it.On older kernels (<= 3,7),
the perf package requires libelf, from the eflutils package. But for
plenty of the features of perf, elfutils backends (libebl) are not
required@runtime. As backporting patches for not depending on
elfutils for all former kernel version is obviously not the best
method, I believe making it possible to not compile/install the
backends of libebl in your rootfs is a legitimate option (saves >300K
(stripped)).

I'll update the patch and resubmit,

br,

Jan

>
> Thanks,
>
> Thomas
> --
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux, Kernel and Android engineering
> http://free-electrons.com

[Buildroot] [PATCH 1/1] elfutils: Add a --{enable, disable}-backends option

[Thomas Petazzoni]

Dear Jan Heylen,

On Thu, 2 Apr 2015 09:12:53 +0200, Jan Heylen wrote:

> > Patches should have a description and a Signed-off-by line.
> Ah, I didn`t realise that on that level it was required, I'll fix it

Yes, we also require a description + SoB *inside* patches for packages.
See
http://buildroot.org/downloads/manual/manual.html#_format_and_licensing_of_the_package_patches.

> > Also, could you submit this patch upstream? I'd like to see if upstream
> > is willing to accept such a patch, since it is more or less a "feature"
> > patch, and we prefer to not have to carry such patches forever.
> This is based on 0002-disable-progs.patch, so it belongs in buildroot?
> I'll try to upstream it to the elfutils package.

Agreed that 0002-disable-progs.patch is basically the same sauce. It
would be great to upstream these patches.

> > This explanation seems weird: why would you link against libelf and not
> > use it?
> 
> The backends are plaform specific implementations, for every supported
> platform. And, e.g. perf package which sources come with the Linux
> kernel has a compile time dependency on it.On older kernels (<= 3,7),
> the perf package requires libelf, from the eflutils package. But for
> plenty of the features of perf, elfutils backends (libebl) are not
> required at runtime. As backporting patches for not depending on
> elfutils for all former kernel version is obviously not the best
> method, I believe making it possible to not compile/install the
> backends of libebl in your rootfs is a legitimate option (saves >300K
> (stripped)).

Ok, understood.

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] [PATCH 1/1] elfutils: Add a --{enable, disable}-backends option

[Jan Heylen]

I immediately consulted the manual, but I admit, I am RTFMed :-s

Jan

On Thu, Apr 2, 2015 at 9:23 AM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Dear Jan Heylen,
>
> On Thu, 2 Apr 2015 09:12:53 +0200, Jan Heylen wrote:
>
>> > Patches should have a description and a Signed-off-by line.
>> Ah, I didn`t realise that on that level it was required, I'll fix it
>
> Yes, we also require a description + SoB *inside* patches for packages.
> See
> http://buildroot.org/downloads/manual/manual.html#_format_and_licensing_of_the_package_patches.
>
>> > Also, could you submit this patch upstream? I'd like to see if upstream
>> > is willing to accept such a patch, since it is more or less a "feature"
>> > patch, and we prefer to not have to carry such patches forever.
>> This is based on 0002-disable-progs.patch, so it belongs in buildroot?
>> I'll try to upstream it to the elfutils package.
>
> Agreed that 0002-disable-progs.patch is basically the same sauce. It
> would be great to upstream these patches.
>
>> > This explanation seems weird: why would you link against libelf and not
>> > use it?
>>
>> The backends are plaform specific implementations, for every supported
>> platform. And, e.g. perf package which sources come with the Linux
>> kernel has a compile time dependency on it.On older kernels (<= 3,7),
>> the perf package requires libelf, from the eflutils package. But for
>> plenty of the features of perf, elfutils backends (libebl) are not
>> required at runtime. As backporting patches for not depending on
>> elfutils for all former kernel version is obviously not the best
>> method, I believe making it possible to not compile/install the
>> backends of libebl in your rootfs is a legitimate option (saves >300K
>> (stripped)).
>
> Ok, understood.
>
> Thomas
> --
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux, Kernel and Android engineering
> http://free-electrons.com