[systemd-devel] [patch] Add -lresolv to libsystemd_intenal_la_LIBADD to prevent underlinking issues

[Samuli Suominen]

On 16/03/14 15:52, Zbigniew Jędrzejewski-Szmek wrote:
> On Sun, Mar 16, 2014 at 10:10:15AM +0200, Samuli Suominen wrote:
>> Since -Wl,-fuse-ld=gold addition, this happens on IA64 arch where binutils's ld gold doesn't support --gc-sections yet:
> Maybe you should just use bfd linker then? Gold was only necessary for the
> ifunc stuff, which is gone anyway. This might to be a better solution, since
> otherwise everything gets an extra lib.

-lresolv is used elsewhere in Makefile.am too, like in
libsystemd_la_LIBADD and test_resolve_LDADD

src/libsystemd/sd-resolve/sd-resolve.c:                         ret =
res_search                   at line 432
src/libsystemd/sd-resolve/sd-resolve.c:                         ret =
res_query                     at line 430

then sd-resolve.c is in libsystemd_internal_la_SOURCES, so adding
-lresolv to libsystemd_internal_la_LIBADD is not a workaround,
but the correct thing to do

>
> LDFLAGS=-Wl,-fuse=bfd ?

we can do that too, but the underlinking issue should still be fixed...
gold is just a more strict linker, which is good, and relying upon
--gc-sections
to 'accidentally' bring in correct libs, is bad practise

>
> Zbyszek
>
>> libtool: link: ia64-unknown-linux-gnu-gcc -shared  -fPIC -DPIC  src/libudev/.libs/libudev_la-libudev.o src/libudev/.libs/libudev_la-libudev-list.o src/libudev/.libs/libudev_la-libu
>> dev-util.o src/libudev/.libs/libudev_la-libudev-device.o src/libudev/.libs/libudev_la-libudev-enumerate.o src/libudev/.libs/libudev_la-libudev-monitor.o src/libudev/.libs/libudev_l
>> a-libudev-queue.o src/libudev/.libs/libudev_la-libudev-hwdb.o  -Wl,--whole-archive ./.libs/libsystemd-internal.a ./.libs/libsystemd-shared.a -Wl,--no-whole-archive  -Wl,--as-needed
>>  -lrt -ldl  -O2 -Wl,--no-undefined -Wl,--gc-sections -Wl,-z -Wl,relro -Wl,-z -Wl,now -Wl,-fuse-ld=gold -Wl,--version-script=/tmp/systemd-211/src/libudev/libudev.sym -Wl,-O1
>> -pthread -Wl,-soname -Wl,libudev.so.1 -o .libs/libudev.so.1.4.0
>> cc1: warning: ./src/core: No such file or directory [enabled by default]
>> /usr/lib/gcc/ia64-unknown-linux-gnu/4.7.3/../../../../ia64-unknown-linux-gnu/bin/ld: Warning: gc-sections option ignored
>> ./.libs/libsystemd-internal.a(libsystemd_internal_la-sd-resolve.o): In function `handle_request':
>> /tmp/systemd-211/src/libsystemd/sd-resolve/sd-resolve.c:432: undefined reference to `__res_search'
>> /tmp/systemd-211/src/libsystemd/sd-resolve/sd-resolve.c:430: undefined reference to `__res_query'
>> collect2: error: ld returned 1 exit status
>> make: *** [libudev.la] Error 1
>>
>> Patch adds -lresolv to libsystemd_internal_la_LIBADD = accordingly, so building works with or without --gc-sections working properly.
>>
>> See also, http://bugs.gentoo.org/show_bug.cgi?id=504700
>>
>>
>> From 2b9ae40d830596eda80cc5bc5252c6685cb75eaa Mon Sep 17 00:00:00 2001
>> From: Samuli Suominen <ssuominen at gentoo.org>
>> Date: Sat, 15 Mar 2014 20:40:24 +0200
>> Subject: [PATCH] Link against -lresolv to prevent linker errors like:
>>  /usr/lib/gcc/ia64-unknown-linux-gnu/4.7.3/../../../../ia64-unknown-
>>  linux-gnu/bin/ld: Warning: gc-sections option ignored
>>  ./.libs/libsystemd-internal.a(libsystemd_internal_la-sd-resolve.o):
>>  In function `handle_request':
>>  /tmp/systemd-211/src/libsystemd/sd-resolve/sd-resolve.c:432: undefined
>>  reference to '__res_search'
>>  /tmp/systemd-211/src/libsystemd/sd-resolve/sd-resolve.c:430: undefined
>>  reference to '__res_query'
>>  
>>  IA64 arch with -fuse-ld=gold doesn't support --gc-sections, which
>>  revealed the underlinking. See Gentoo bug 504700.
>>
>> ---
>>  Makefile.am | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/Makefile.am b/Makefile.am
>> index 9e01cd5..4b8a081 100644
>> --- a/Makefile.am
>> +++ b/Makefile.am
>> @@ -2121,7 +2121,8 @@ libsystemd_internal_la_CFLAGS = \
>>  	-pthread
>>  
>>  libsystemd_internal_la_LIBADD = \
>> -	$(RT_LIBS)
>> +	$(RT_LIBS) \
>> +	-lresolv
>>  
>>  noinst_LTLIBRARIES += \
>>  	libsystemd-internal.la
>> --