[Buildroot] [PATCH v3 1/1] package/mono: fix external libatomic_ops linkage

[Arnout Vandecappelle]

On 08/09/2021 20:08, Illia Bitkov wrote:
> Added patch fixes linkage of libgc with external libtomic-ops.
> Mono uses bundeled bdwgc which doesn't link external libatomic-ops.
> Patch is a fix cherry-picked from bdwgc upstream.
> 
> Problem found on ARMv5 processors, on newer ARM processors
> it uses header based functions and doesn't need built library.
> 
> Error:
> /home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/bin/../lib/gcc/arm-buildroot-linux-uclibcgnueabi/9.3.0/../../../../arm-buildroot-linux-uclibcgnueabi/bin/ld: ../../external/bdwgc/.libs/libgc.a(gc.o): in function `GC_steal_mark_stack':
> gc.c:(.text+0x2020): undefined reference to `AO_store_full_emulation'
> 
> Fixes:
> http://autobuild.buildroot.net/results/ebc54e5dea63aca21a4072d294fdede41de559c7
> http://autobuild.buildroot.net/results/6d10a4bd43fbc9c1d3fa26d5eef394c8023cb85f
> Signed-off-by: Illia Bitkov <illia.bitkov at mind.be>

  Leave an empty line before the Signed-off-by.

  Applied to master with that fixed, thanks.

  Regards,
  Arnout

> ---
>   ...-system-libatomic_ops-shared-library.patch | 52 +++++++++++++++++++
>   1 file changed, 52 insertions(+)
>   create mode 100644 package/mono/0001-Fix-linkage-with-a-system-libatomic_ops-shared-library.patch
> 
> diff --git a/package/mono/0001-Fix-linkage-with-a-system-libatomic_ops-shared-library.patch b/package/mono/0001-Fix-linkage-with-a-system-libatomic_ops-shared-library.patch
> new file mode 100644
> index 0000000000..66d4d8e100
> --- /dev/null
> +++ b/package/mono/0001-Fix-linkage-with-a-system-libatomic_ops-shared-library.patch
> @@ -0,0 +1,52 @@
> +From 02a44ee1df8176c72e75fd706d1a8f063d3196d5 Mon Sep 17 00:00:00 2001
> +From: Fabrice Fontaine <fontaine.fabrice at gmail.com>
> +Date: Mon, 5 Nov 2018 22:50:40 +0100
> +Subject: Fix linkage with a system libatomic_ops shared library
> +
> +Issue #247 (bdwgc).
> +
> +When bdwgc is linked with the external libatomic_ops, bdw-gc.pc must
> +contain the needed dynamic libraries (such as -latomic_ops) otherwise
> +build of applications could fail on the link stage on some hosts:
> +* libgc.so: undefined reference to 'AO_fetch_compare_and_swap_emulation'
> +* libgc.so: undefined reference to 'AO_store_full_emulation'
> +
> +So, this commit sets ATOMIC_OPS_LIBS to "-latomic_ops" when a system
> +atomic_ops library is used and uses ATOMIC_OPS_LIBS in bdw-gc.pc.in.
> +
> +* bdw-gc.pc.in (Libs): Add @ATOMIC_OPS_LIBS at .
> +* configure.ac [$with_libatomic_ops!=no && $with_libatomic_ops!=none
> +&& $THREADS!=none] (ATOMIC_OPS_LIBS): Set to -latomic_ops; do AC_SUBST.
> +
> +Fix is cherry-picked from bdwgc upstream
> +
> +Link to original commit https://github.com/ivmai/bdwgc/commit/02a44ee1df8176c72e75fd706d1a8f063d3196d5?branch=02a44ee1df8176c72e75fd706d1a8f063d3196d5&diff=unified
> +
> +Signed-off-by: Illia Bitkov <illia.bitkov at mind.be>
> +
> +diff --git a/external/bdwgc/bdw-gc.pc.in b/external/bdwgc/bdw-gc.pc.in
> +index ef4c2341..a32e7598 100644
> +--- a/external/bdwgc/bdw-gc.pc.in
> ++++ b/external/bdwgc/bdw-gc.pc.in
> +@@ -6,5 +6,5 @@ includedir=@includedir@
> + Name: Boehm-Demers-Weiser Conservative Garbage Collector
> + Description: A garbage collector for C and C++
> + Version: @PACKAGE_VERSION@
> +-Libs: -L${libdir} -lgc
> ++Libs: -L${libdir} @ATOMIC_OPS_LIBS@ -lgc
> + Cflags: -I${includedir}
> +diff --git a/external/bdwgc/configure.ac b/external/bdwgc/configure.ac
> +index 21abe8fa..9ffe81de 100644
> +--- a/external/bdwgc/configure.ac
> ++++ b/external/bdwgc/configure.ac
> +@@ -1081,7 +1081,9 @@ AS_IF([test x"$with_libatomic_ops" = xno \
> + AC_MSG_CHECKING([which libatomic_ops to use])
> + AS_IF([test x"$with_libatomic_ops" != xno],
> +   [ AS_IF([test x"$with_libatomic_ops" != xnone -a x"$THREADS" != xnone],
> +-          [ AC_MSG_RESULT([external]) ],
> ++          [ AC_MSG_RESULT([external])
> ++            ATOMIC_OPS_LIBS="-latomic_ops"
> ++            AC_SUBST([ATOMIC_OPS_LIBS]) ],
> +           [ AC_MSG_RESULT([none])
> +             AS_IF([test x"$THREADS" != xnone],
> +                   [ AC_DEFINE([GC_BUILTIN_ATOMIC], [1],
>