Re: [dpdk-dev] [PATCH v2 2/4] buildtools: get static mlx dependencies for meson

[Bruce Richardson <bruce.richardson@intel.com>]

On Mon, Jan 27, 2020 at 04:44:00PM +0100, Thomas Monjalon wrote:
> The shell script options-ibverbs-static.sh was used with make
> in forcing static linkage of ibverbs libraries.
> 
> When choosing to link with a static dependency in meson,
> the generated .pc file will not force such static linkage.
> The solution will rely on using this script in meson.
> 
> If linking with libraries installed in a non-standard path,
> an option -L is provided via EXTRA_LDFLAGS in case of using make.
> With meson, tuning PKG_CONFIG_PATH for pkg-config should be enough.
> When statically linking an application, the .pc file must save the
> -L path so the application link will work without any extra option.
> That's why --libs-only-l is replaced with --libs which includes -L.
> Options which are neither -l or -L are filtered out because not needed
> and can cause compilation issues with the legacy system using make.
> 
> The other change in this script is to move the main library file
> (libiverbs.a) at the end of the list of dependencies.
> It fixes some undefined references when linking a static application
> using libdpdk.pc.
> 
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> ---
>  buildtools/options-ibverbs-static.sh | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/buildtools/options-ibverbs-static.sh b/buildtools/options-ibverbs-static.sh
> index 0f285a343b..43578a37f3 100755
> --- a/buildtools/options-ibverbs-static.sh
> +++ b/buildtools/options-ibverbs-static.sh
> @@ -9,6 +9,12 @@
>  #
>  # PKG_CONFIG_PATH may be required to be set if libibverbs.pc is not installed.
>  
> -pkg-config --libs-only-l --static libibverbs |
> +lib='libibverbs'
> +deps='pthread|nl'
> +
> +pkg-config --libs --static $lib |
>  	tr '[:space:]' '\n' |
> -	sed -r '/^-l(pthread|nl)/! s,(^-l)(.*),\1:lib\2.a,'
> +	sed -r "/^-l($deps)/! s,(^-l)(.*),\1:lib\2.a," |   # explicit .a
> +	sed -n '/^-[Ll]/p' |   # extra link options may break with make
> +	sed "/$lib/d"   # move main lib at the end
> +echo -l:$lib.a

To improve my understanding of the desired end result with this patchset
applied, I tried running different build configs with make with this patch
applied. I get a build error on my system with the following settings
adjusted from default (i.e. shared build with static link of ibverbs):

diff .config.orig .config
32c32
< CONFIG_RTE_BUILD_SHARED_LIB=n
---
> CONFIG_RTE_BUILD_SHARED_LIB=y
219c219
< CONFIG_RTE_LIBRTE_MLX5_PMD=n
---
> CONFIG_RTE_LIBRTE_MLX5_PMD=y
225c225
< CONFIG_RTE_IBVERBS_LINK_STATIC=n
---
> CONFIG_RTE_IBVERBS_LINK_STATIC=y

Error message I got is below. This is on Ubuntu 19.10 with gcc 9.2:

  LD librte_pmd_mlx5.so.20.0.1
/usr/bin/ld: /lib/x86_64-linux-gnu/libmlx5.a(mlx5.c.o): relocation R_X86_64_PC32 against symbol `stderr@@GL
/usr/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status
make[5]: *** [/home/bruce/dpdk.org/mk/rte.lib.mk:100: librte_pmd_mlx5.so.20.0.1] Error 1
make[4]: *** [/home/bruce/dpdk.org/mk/rte.subdir.mk:35: mlx5] Error 2
make[3]: *** [/home/bruce/dpdk.org/mk/rte.subdir.mk:35: net] Error 2
make[2]: *** [/home/bruce/dpdk.org/mk/rte.sdkbuild.mk:48: drivers] Error 2
make[1]: *** [/home/bruce/dpdk.org/mk/rte.sdkroot.mk:99: all] Error 2
make: *** [Makefile:12: all] Error 2