Re: [Buildroot] [PATCH] package/numactl: point to target libs via LDFLAGS

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello Alexey,

On Mon, 24 Oct 2022 19:49:11 +0200
Alexey Brodkin via buildroot <buildroot@buildroot.org> wrote:

> In the commit a699a667bd64 ("package/numactl: add -latomic to numa.pc")
> we opted-out from unconditional linking with "-latomic" and made it
> a conditional based on real availability of __atomic_fetch_and_1()
> in the toolchain. I.e. for many targets "-latomic" was not used
> any longer.
> 
> And in those supposedly rare cases when libatomic was required it was
> all OK until there's a LD_LIBRARY_PATH set with something where yet
> another libatomic.so instance exists, especially if that's the one from
> host (in my case I used a separately built host toolchain). Then we see:
> ---------------------->8-----------------------  
> /bin/sh ./libtool  --tag=CC   --mode=link .../buildroot/output/host/bin/arc32-buildroot-linux-uclibc-gcc -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -Os -g0  -Wl,-z,max-page-size=4096 -fPIC -std=gnu99    -o numastat numastat-numastat.o  -latomic
> 
> libtool: link: .../buildroot/output/host/bin/arc32-buildroot-linux-uclibc-gcc -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g0 -Wl,-z -Wl,max-page-size=4096 -fPIC -std=gnu99 -o numastat numastat-numastat.o  .../gcc-5.2.0/lib/../lib64/libatomic.so -pthread -Wl,-rpath -Wl,.../gcc-5.2.0/lib/../lib64 -Wl,-rpath -Wl,.../gcc-5.2.0/lib/../lib64
> .../buildroot/output/host/lib/gcc/arc32-buildroot-linux-uclibc/12.2.1/../../../../arc32-buildroot-linux-uclibc/bin/ld: .../gcc-5.2.0/lib/../lib64/libatomic.so: error adding symbols: file in wrong format
> collect2: error: ld returned 1 exit status
> ---------------------->8-----------------------  
> 
> That happens because libtool of numactl adds contents of the aforementioned
> LD_LIBRARY_PATH to its "$searchdirs" and then the first libatomic.so it
> finds becomes the one used for linking. What's more our precios cross-built
> libatomic.so never even gets considered because that first found libatomic.so
> is used with full path, not as "-latomic" as otherwise it would have been used
> without helpful libtool.

Thanks for the patch. However, I don't get it. Where is LD_LIBRARY_PATH
defined? Do you have a reproducer for this issue?

> +NUMACTL_CONF_ENV = CFLAGS="$(TARGET_CFLAGS) -fPIC" \
> +		   LDFLAGS="$(TARGET_LDFLAGS) -L$(STAGING_DIR)/lib"

This is really a red flag, $(STAGING_DIR)/lib is already in the default
search path of the compiler, so that should never be needed.

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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