RE: [PATCH] perf build: Fix library not found error when using CSLIBS

[Pandey, Radhey Shyam]

> -----Original Message-----
> From: James Clark <james.clark@xxxxxxx>
> Sent: Friday, July 7, 2023 9:16 PM
> To: linux-perf-users@xxxxxxxxxxxxxxx; Pandey, Radhey Shyam
> <radhey.shyam.pandey@xxxxxxx>
> Cc: coresight@xxxxxxxxxxxxxxxx; James Clark <james.clark@xxxxxxx>; Peter
> Zijlstra <peterz@xxxxxxxxxxxxx>; Ingo Molnar <mingo@xxxxxxxxxx>;
> Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>; Mark Rutland
> <mark.rutland@xxxxxxx>; Alexander Shishkin
> <alexander.shishkin@xxxxxxxxxxxxxxx>; Jiri Olsa <jolsa@xxxxxxxxxx>;
> Namhyung Kim <namhyung@xxxxxxxxxx>; Ian Rogers <irogers@xxxxxxxxxx>;
> Adrian Hunter <adrian.hunter@xxxxxxxxx>; Uwe Kleine-König <uwe@kleine-
> koenig.org>; linux-kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH] perf build: Fix library not found error when using CSLIBS
> 
> -L only specifies the search path for libraries directly provided in the link line
> with -l. Because -lopencsd isn't specified, it's only linked because it's a
> dependency of -lopencsd_c_api. Dependencies like this are resolved using
> the default system search paths or -rpath-link=... rather than -L. This means
> that compilation only works if OpenCSD is installed to the system rather than
> provided with the CSLIBS (-L) option.
> 
> This could be fixed by adding -Wl,-rpath-link=$(CSLIBS) but that is less
> conventional than just adding -lopencsd to the link line so that it uses -L. -
> lopencsd seems to have been removed in commit ed17b1914978 ("perf
> tools: Drop requirement for libstdc++.so for libopencsd check") because it
> was thought that there was a chance compilation would work even if it didn't
> exist, but I think that only applies to libstdc++ so there is no harm to add it
> back. libopencsd.so and libopencsd_c_api.so would always exist together.
> 
> Testing
> =======
> 
> The following scenarios now all work:
> 
>  * Cross build with OpenCSD installed
>  * Cross build using CSLIBS=...
>  * Native build with OpenCSD installed
>  * Native build using CSLIBS=...
>  * Static cross build with OpenCSD installed
>  * Static cross build with CSLIBS=...
> 
> Reported-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxx>
> Closes: https://lore.kernel.org/linux-arm-kernel/56905d7a-a91e-883a-b707-
> 9d5f686ba5f1@xxxxxxx/
> Link: https://lore.kernel.org/all/36cc4dc6-bf4b-1093-1c0a-
> 876e368af183@xxxxxxxxxxxxxxxxx/
> Fixes: ed17b1914978 ("perf tools: Drop requirement for libstdc++.so for
> libopencsd check")
> Signed-off-by: James Clark <james.clark@xxxxxxx>
> ---
>  tools/perf/Makefile.config | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config index
> 0609c19caabd..c5db0de49868 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -155,9 +155,9 @@ FEATURE_CHECK_LDFLAGS-libcrypto = -lcrypto  ifdef
> CSINCLUDES
>    LIBOPENCSD_CFLAGS := -I$(CSINCLUDES)
>  endif
> -OPENCSDLIBS := -lopencsd_c_api
> +OPENCSDLIBS := -lopencsd_c_api -lopencsd
>  ifeq ($(findstring -static,${LDFLAGS}),-static)
> -  OPENCSDLIBS += -lopencsd -lstdc++
> +  OPENCSDLIBS += -lstdc++
>  endif
>  ifdef CSLIBS
>    LIBOPENCSD_LDFLAGS := -L$(CSLIBS)
> --
> 2.34.1

Tested-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxx>
Cross compiled for aarch64 on x86_64.

make ARCH=arm64 NO_LIBELF=1 NO_JVMTI=1 VF=1 CORESIGHT=1 -C  tools/perf

file <snip>/linux-xlnx/tools/perf/perf
perf: ELF 64-bit LSB shared object, ARM aarch64, version 1 (SYSV), 
dynamically linked, interpreter /lib/ld-linux-aarch64.so.1, 
BuildID[sha1]=ef7c524338577b14e7c0f914d882dec4d26e93a2, 
for GNU/Linux 3.14.0, with debug_info, not stripped

Thanks,
Radhey