Re: [dpdk-dev] [PATCH 1/4] app: add LDFLAGS -latomic to link atomic lib

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

-----Original Message-----
> Date: Tue, 15 May 2018 04:28:41 -0400
> From: Gavin Hu <gavin.hu@arm.com>
> To: dev@dpdk.org
> Subject: [dpdk-dev] [PATCH 1/4] app: add LDFLAGS -latomic to link atomic lib
> X-Mailer: git-send-email 2.1.4
> 
> For ARM64 platform, libdpdk.a includes the librte_pmd_octeontx_ssovf.a,
> which requires the libatomic.a support.The atomic lib is built-in in the
> gcc toolchain, but for clang it has to be explicitly linked.
> For more details, please refer to https://clang.llvm.org/docs/Toolchain.html
> 
> ~/dpdk/build/lib/librte_pmd_octeontx_ssovf.a(timvf_worker.o): In function `timvf_timer_cancel_burst':
> timvf_worker.c:(.text+0x80): undefined reference to `__atomic_fetch_add_8'
> /home/gavin/arm_repo/dpdk/build/lib/librte_pmd_octeontx_ssovf.a(timvf_worker.o): In function `timvf_timer_arm_burst_sp':
> timvf_worker.c:(.text+0x200): undefined reference to `__atomic_fetch_add_8'
> timvf_worker.c:(.text+0x244): undefined reference to `__atomic_store_2'
> timvf_worker.c:(.text+0x278): undefined reference to `__atomic_fetch_add_4'
> timvf_worker.c:(.text+0x30c): undefined reference to `__atomic_store_2'
> 
> Signed-off-by: Gavin Hu <gavin.hu@arm.com>
> Reviewed-by: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>



Following patch is part of upstream. Are you testing with following
patch/upstream.

commit 55fbc92d7800100628579643c9ee2770614fef10
Author: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
Date:   Wed May 9 02:56:00 2018 +0530

    event/octeontx: fix build with clang 6
    
    Clang 6 & 7 fail to naturally align packed structs due to this clang
    can't use 8byte atomic primitives and splits them into lesser atomic
    primitives. To use lesser atomic primitives we need to link
libatomic
    (-latomic), instead supply alignment attribute to the compiler.
    
    timvf_worker.c:(.text+0x498): undefined reference to
`__atomic_fetch_add_8'
    timvf_worker.c:(.text+0x525): undefined reference to
`__atomic_store_2'
    timvf_worker.c:(.text+0x557): undefined reference to
`__atomic_fetch_add_4'
    timvf_worker.c:(.text+0x5de): undefined reference to
`__atomic_store_2'
    
    Fixes: f874c1eb1519 ("event/octeontx: create and free timer
adapter")
    
    Reported-by: Andrew Rybchenko <arybchenko@solarflare.com>
    Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
    Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>


> ---
>  mk/rte.app.mk | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mk/rte.app.mk b/mk/rte.app.mk
> index 438f99d..bca8325 100644
> --- a/mk/rte.app.mk
> +++ b/mk/rte.app.mk
> @@ -51,6 +51,7 @@ endif
>  
>  # Link only the libraries used in the application
>  LDFLAGS += --as-needed
> +LDFLAGS += -latomic
>  
>  # default path for libs
>  _LDLIBS-y += -L$(RTE_SDK_BIN)/lib
> -- 
> 2.1.4
>