[Buildroot] [PATCH] kmod: disable --gc-sections ld option when building for xtensa

[Buildroot] [PATCH] kmod: disable --gc-sections ld option when building for xtensa

[Max Filippov]

This is a workaround for the following ld issue exhibited by --gc-sections
option, until a proper fix for binutils is ready:

ld: BFD (GNU Binutils) 2.22 internal error, aborting at elf32-xtensa.c line 3374 in elf_xtensa_finish_dynamic_sections

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 package/kmod/900-disable-gc-sections.patch.xtensa | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 package/kmod/900-disable-gc-sections.patch.xtensa

diff --git a/package/kmod/900-disable-gc-sections.patch.xtensa b/package/kmod/900-disable-gc-sections.patch.xtensa
new file mode 100644
index 0000000..2b7a9cb
--- /dev/null
+++ b/package/kmod/900-disable-gc-sections.patch.xtensa
@@ -0,0 +1,12 @@
+--- kmod-16/configure	2013-12-23 01:31:12.456202872 +0400
++++ kmod-16.mod/configure	2014-03-04 22:53:37.132241845 +0400
+@@ -14511,8 +14511,7 @@
+ 
+ 
+   for flag in  \
+-		       -Wl,--as-needed \
+-		       -Wl,--gc-sections; do
++		       -Wl,--as-needed ; do
+ 
+   { $as_echo "$as_me:${as_lineno-$LINENO}: checking if $CC supports flag $flag in envvar LDFLAGS" >&5
+ $as_echo_n "checking if $CC supports flag $flag in envvar LDFLAGS... " >&6; }
-- 
1.8.1.4

[Buildroot] [PATCH] kmod: disable --gc-sections ld option when building for xtensa

[Thomas Petazzoni]

Dear Max Filippov,

On Tue,  4 Mar 2014 23:10:16 +0400, Max Filippov wrote:
> This is a workaround for the following ld issue exhibited by --gc-sections
> option, until a proper fix for binutils is ready:
> 
> ld: BFD (GNU Binutils) 2.22 internal error, aborting at elf32-xtensa.c line 3374 in elf_xtensa_finish_dynamic_sections
> 
> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
> ---
>  package/kmod/900-disable-gc-sections.patch.xtensa | 12 ++++++++++++

The patch should be named kmod-01-<description>.patch. We no longer
accept architecture-specific patches, so the .xtensa extension has to
go, and we have to ensure that the fix is usable on all architectures.

So either we simply remove --gc-sections on all architecture, or the
configure.ac test has to be made conditional on xtensa.

>  1 file changed, 12 insertions(+)
>  create mode 100644 package/kmod/900-disable-gc-sections.patch.xtensa
> 
> diff --git a/package/kmod/900-disable-gc-sections.patch.xtensa b/package/kmod/900-disable-gc-sections.patch.xtensa
> new file mode 100644
> index 0000000..2b7a9cb
> --- /dev/null
> +++ b/package/kmod/900-disable-gc-sections.patch.xtensa

The patch lacks a description. See
http://buildroot.org/downloads/manual/manual.html#patch-policy for more
details about the format of the patches.

> @@ -0,0 +1,12 @@
> +--- kmod-16/configure	2013-12-23 01:31:12.456202872 +0400
> ++++ kmod-16.mod/configure	2014-03-04 22:53:37.132241845 +0400
> +@@ -14511,8 +14511,7 @@

We normally prefer to patch configure.ac, and add KMOD_AUTORECONF = YES.

All that being said, I believe there is a much simpler solution. Don't
use any patch at all, and add:

# --gc-sections triggers a bug in the current Xtensa binutils
ifeq ($(BR2_xtensa),y)
KMOD_CONF_ENV += cc_cv_LDFLAGS__Wl___gc_sections=no
endif

to package/kmod/kmod.mk.

Can you test that it works for you, and submit the corresponding patch?

Thanks!

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

[Buildroot] [PATCH] kmod: disable --gc-sections ld option when building for xtensa

[Max Filippov]

Hi Thomas,

On Tue, Mar 4, 2014 at 11:22 PM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> On Tue,  4 Mar 2014 23:10:16 +0400, Max Filippov wrote:
>> This is a workaround for the following ld issue exhibited by --gc-sections
>> option, until a proper fix for binutils is ready:
>>
>> ld: BFD (GNU Binutils) 2.22 internal error, aborting at elf32-xtensa.c line 3374 in elf_xtensa_finish_dynamic_sections
>>
>> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
>> ---
>>  package/kmod/900-disable-gc-sections.patch.xtensa | 12 ++++++++++++

[...]

> I believe there is a much simpler solution. Don't
> use any patch at all, and add:
>
> # --gc-sections triggers a bug in the current Xtensa binutils
> ifeq ($(BR2_xtensa),y)
> KMOD_CONF_ENV += cc_cv_LDFLAGS__Wl___gc_sections=no
> endif
>
> to package/kmod/kmod.mk.
>
> Can you test that it works for you, and submit the corresponding patch?

thank you for the review and for the suggested solution, it works for me
and I like it, though it doesn't look obvious. I'll submit v2.

-- 
Thanks.
-- Max