| Message ID | 20170820210151.2242-1-thomas.petazzoni@free-electrons.com |
|---|---|
| State | Accepted |
| Headers | show |
Hello, On Sun, 20 Aug 2017 23:01:51 +0200, Thomas Petazzoni wrote: > libunwind configure script explicitly links libunwind against > libgcc_s. libgcc_s is only guaranteed to be available for toolchains > that supports dynamic linking: pure static linking toolchains only > have libgcc.a, not libgcc_s.so. > > Therefore, let's make libunwind unavailable on toolchains that lack > dynamic linking support. We could potentially support linking with > libgcc, but switching to libgcc_s was done upstream because libgcc was > lacking some symbols on ARM > (https://lists.nongnu.org/archive/html/libunwind-devel/2014-06/msg00024.html). Even > though recent gcc versions seem to provide such symbols in libgcc.a, > having libunwind available on static linking configurations is not a > useful enough use-case to do the necessary research to find when this > issue was fixed in gcc. > > Since libunwind is not used as a mandatory dependency in any package, > adding this !BR2_STATIC_LIBS dependency is trivial and nicely avoids > the problematic situation. > > This fixes two different autobuilder failures: > > - Gstreamer 1.x programs failing to link, because libunwind links > against libgcc_s that isn't available (static linking > configuration): > > http://autobuild.buildroot.net/results/9d4fbf7167e9afce0eef5c9e0cfd42c966ecba36/ > > - Gmrender-resurrect, which fails to link, because GStreamer 1.x uses > some libunwind functionality, but does not take into account the > libunwind dependency in its .pc files (static linking > configuration): > > http://autobuild.buildroot.net/results/0a3a2485c187a000482c178f1e9c64dd716a858f/ > > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> > --- > package/libunwind/Config.in | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) Applied to master, thanks. Thomas
diff --git a/package/libunwind/Config.in b/package/libunwind/Config.in index 1a25317..be576d1 100644 --- a/package/libunwind/Config.in +++ b/package/libunwind/Config.in @@ -22,11 +22,14 @@ config BR2_PACKAGE_LIBUNWIND bool "libunwind" depends on BR2_TOOLCHAIN_HAS_THREADS depends on BR2_PACKAGE_LIBUNWIND_ARCH_SUPPORTS + # forcefully links against libgcc_s, only available in dynamic + # linking configurations + depends on !BR2_STATIC_LIBS help C API to determine the call-chain of a program. http://www.nongnu.org/libunwind/index.html -comment "libunwind needs a toolchain w/ threads" +comment "libunwind needs a toolchain w/ threads, dynamic library" depends on BR2_PACKAGE_LIBUNWIND_ARCH_SUPPORTS - depends on !BR2_TOOLCHAIN_HAS_THREADS + depends on !BR2_TOOLCHAIN_HAS_THREADS || BR2_STATIC_LIBS
libunwind configure script explicitly links libunwind against libgcc_s. libgcc_s is only guaranteed to be available for toolchains that supports dynamic linking: pure static linking toolchains only have libgcc.a, not libgcc_s.so. Therefore, let's make libunwind unavailable on toolchains that lack dynamic linking support. We could potentially support linking with libgcc, but switching to libgcc_s was done upstream because libgcc was lacking some symbols on ARM (https://lists.nongnu.org/archive/html/libunwind-devel/2014-06/msg00024.html). Even though recent gcc versions seem to provide such symbols in libgcc.a, having libunwind available on static linking configurations is not a useful enough use-case to do the necessary research to find when this issue was fixed in gcc. Since libunwind is not used as a mandatory dependency in any package, adding this !BR2_STATIC_LIBS dependency is trivial and nicely avoids the problematic situation. This fixes two different autobuilder failures: - Gstreamer 1.x programs failing to link, because libunwind links against libgcc_s that isn't available (static linking configuration): http://autobuild.buildroot.net/results/9d4fbf7167e9afce0eef5c9e0cfd42c966ecba36/ - Gmrender-resurrect, which fails to link, because GStreamer 1.x uses some libunwind functionality, but does not take into account the libunwind dependency in its .pc files (static linking configuration): http://autobuild.buildroot.net/results/0a3a2485c187a000482c178f1e9c64dd716a858f/ Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> --- package/libunwind/Config.in | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)