[erlang-questions] Erlang on 64-bit ARM?
Sun Jan 17 12:14:12 CET 2016
Frank Hunleth writes:
> I was wondering if anyone uses Erlang on a 64-bit ARM platform
> (aarch64)? The Buildroot project's CI servers are throwing linker
> errors such as the following:
> LD /home/buildroot/autobuild/run/instance-0/output/build/erlang-17.5/bin/aarch64-buildroot-linux-gnu/child_setup
> AR /home/buildroot/autobuild/run/instance-0/output/build/erlang-17.5/erts/emulator/pcre/obj/aarch64-buildroot-linux-gnu/opt/libepcre.a
> LD /home/buildroot/autobuild/run/instance-0/output/build/erlang-17.5/bin/aarch64-buildroot-linux-gnu/beam
> In function `AO_double_compare_and_swap':
> ethr_atomics.c:(.text+0x20): undefined reference to
> In function `AO_double_load':
> ethr_atomics.c:(.text+0x3c): undefined reference to `__atomic_load_16'
> In function `ethr_dw_atomic_cmpxchg_acqb':
> ethr_atomics.c:(.text+0x5e8): undefined reference to `__atomic_load_16'
> See http://autobuild.buildroot.net/results/0cd/0cd22eb74fa29e5a85bf897762e16ab3daf33962/build-end.log
> for all of the error messages.
> I was able to reproduce the same errors on the 18.2.1 release as well.
> Possibly confounding the situation is that Buildroot crosscompiles
> Erlang. However, Erlang builds fine on all other platforms supported
> by Buildroot, and my attempt at reading the atomic intrinsics code was
> leading me down the path that aarch64 may not be supported. Could
> somewhere verify whether this is the case?
OTP 18.2.1 builds fine using an aarch64-unknown-linux cross toolchain built
using binutils-2.25.1, gcc-5.3.0, linux-3.19 kernel headers, and glibc-2.22,
all unmodified upstream sources.
However, if I also build and install libatomic_ops in that cross toolchain
and add --with-libatomic_ops to OTP's ./configure, then I do get the same
error as you cite above.
Looks like some issue in OTP's interface to that library. I've never looked
into libatomics_ops myself, since I prefer to implement atomics by hand or by
using gcc's builtins.
Workaround for now is to not use libatomic_ops. You may also want to file a
bug in the bug tracker.
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