-----Original Message----- > Date: Wed, 16 May 2018 02:08:48 +0000 > From: Gavin Hu <gavin...@arm.com> > To: "dev@dpdk.org" <dev@dpdk.org>, "Jacob, Jerin" > <jerin.jacobkollanukka...@cavium.com> > Subject: Re: [dpdk-dev] dev Digest, Vol 195, Issue 45 > > > > > 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...@arm.com> > > Reviewed-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com> > > > > Following patch is part of upstream. Are you testing with following > patch/upstream. > > With this patch from Nikhilesh, this __ atomic__ compiling issue was gone. > The two patches fix the same issue. > Should I abandon my patch?
The root cause is analyzed, the -latomic needs only when atomic operations on variable are not aligned. The fix added to align variable where it was not correct.This fix the performance issue as well, adding -latomic will simply hide the problem by not letting to know the alignment/performance issue. IMO, If there is no dependency with -latomic in current code base then we should NOT add new dependency. > > I see this note on: https://clang.llvm.org/docs/Toolchain.html > Note > Clang does not currently automatically link against libatomic when using > libgcc_s. You may need to manually add -latomic to support this configuration > when using non-native atomic operations (if you see link errors referring to > __atomic_* functions). > > commit 55fbc92d7800100628579643c9ee2770614fef10 > Author: Pavan Nikhilesh <pbhagavat...@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 <arybche...@solarflare.com> > Signed-off-by: Pavan Nikhilesh <pbhagavat...@caviumnetworks.com> > Acked-by: Jerin Jacob <jerin.ja...@caviumnetworks.com>
