From 97e9db4332aeb58c5b83536426906df942573d4d Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Wed, 19 Aug 2015 13:08:45 +0200 Subject: [PATCH] libpthsem: fix setjmp/longjmp detection libpthsem has been affected since quite a while by build issues, but occuring only on Nathaniel Roach's autobuilder. The failure message is: error: #error "Unsupported Linux (g)libc version and/or platform" This message comes from pth_mctx.c file, which implements five methods for machine context initialization: VARIANT 1: THE STANDARDIZED SVR4/SUSv2 APPROACH VARIANT 2: THE SIGNAL STACK TRICK VARIANT 3: LINUX SPECIFIC JMP_BUF FIDDLING VARIANT 4: INTERACTIVE SPECIFIC JMP_BUF FIDDLING VARIANT 5: WIN32 SPECIFIC JMP_BUF FIDDLING The "Unsupported (g)libc version and/or platform" only appears when "VARIANT 4" is used, since VARIANT 4 only supports a very limited number of platforms. So when building with Nathaniel's autobuilder, VARIANT 4 is chosen. However, when you build libpthsem on some other machine than Nathaniel's autobuilder, VARIANT 2 is chosen, and works regardless of the glibc version or architecture. VARIANT 2 is chosen when: !PTH_MCTX_DSP(sjljlx) &&\ !PTH_MCTX_DSP(sjljisc) &&\ !PTH_MCTX_DSP(sjljw32) On both Nathaniel's autobuilder, and on a different machine, the PTH_MCTX_MTH macro gives sjlj: #define PTH_MCTX_MTH_use PTH_MCTX_MTH_sjlj However, on a "normal" machine, the PTH_MCTX_DSP macro gives ssjlj: #define PTH_MCTX_DSP_use PTH_MCTX_DSP_ssjlj While on Nathaniel's autobuilder, it gives: #define PTH_MCTX_DSP_use PTH_MCTX_DSP_sjljlx This explains why VARIANT 4 is being used on Nathaniel's autobuilder, while VARIANT 2 is used when building on other platforms. The decision of the value for PTH_MCTX_DSP is derived as follows in configure.ac: AC_CHECK_SJLJ(sjlj=yes, sjlj=no, sjlj_type) [...] elif test ".$sjlj" = .yes; then mctx_mth=sjlj mctx_dsp=$sjlj_type [...] AC_DEFINE_UNQUOTED(PTH_MCTX_DSP_use, [PTH_MCTX_DSP_$mctx_dsp], [define for machine context dispatching]) So basically, the value of PTH_MCTX_DSP is $sjlj_type, as returned by the AC_CHECK_SJLJ autoconf macro, implemented in acinclude.m4. However, reading this macro is quite informative: it does a number of tests that are not cross-compile friendly. Especially, it looks at the kernel version with 'uname -r' to decide whether the Linux system is braindead or not. If the system runs a 2.2.x kernel or newer 2.x, or a 3.x kernel, everything is fine, the system is not braindead, and sjlj_type is set to ssjlj. However, if the build system runs a 4.x kernel, then it is considered as braindead, and sjlj_type is set to sjljlx. And indeed, Nathaniel's autobuilder is running a 4.x kernel, while all other autobuilders run 2.x or 3.x kernels. Since for all sane Linux systems, this AC_CHECK_SJLJ macro concludes that the setjmp/longtmp type is ssjlj, this commit takes the simplest route of forcing this value, skipping the broken detection. Note that we're overriding ac_cv_check_sjlj instead of using the --with-mctx-* options, since the latter do not work properly in the context of Nathaniel's autobuilder, as the broken cross-compilation tests continue to cause problems. Fixes: http://autobuild.buildroot.org/results/3dd/3dd66d70c2e36f2d9fb0a0fe01bbdec009d55067/ and many similar build failures This patch has been tested by Nathaniel Roach in the context of his autobuilder instance which was causing the original problem. Tested-by: Nathaniel Roach Signed-off-by: Thomas Petazzoni Tested-by: "Yann E. MORIN" Signed-off-by: Peter Korsgaard --- package/libpthsem/libpthsem.mk | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/package/libpthsem/libpthsem.mk b/package/libpthsem/libpthsem.mk index f9f6f71813..b8a3d7d561 100644 --- a/package/libpthsem/libpthsem.mk +++ b/package/libpthsem/libpthsem.mk @@ -13,6 +13,20 @@ LIBPTHSEM_AUTORECONF = YES LIBPTHSEM_INSTALL_STAGING = YES LIBPTHSEM_CONFIG_SCRIPTS = pthsem-config +# Force the setjmp/longjmp detection, because the test being done in +# the AC_CHECK_SJLJ macro is not cross-compilation safe: it checks the +# running kernel with 'uname -r', and checks the C library version by +# looking at /usr/include/features.h. In terms of kernel version, it +# assumes any version later than 2.2.x is fine, except that it doesn't +# recognize 4.x as a valid kernel version, recognizing such systems as +# "braindead" and therefore falling back to the 'sjljlx' value for +# ac_cv_check_sjlj. In terms of C library version, it wants +# __GLIBC_MINOR to be at least 1. Since both conditions are true for +# all Buildroot systems, we can simply force the setjmp/longjmp +# detection to ssjlj. +LIBPTHSEM_CONF_ENV += \ + ac_cv_check_sjlj=ssjlj + ifeq ($(BR2_PACKAGE_LIBPTHSEM_COMPAT),y) LIBPTHSEM_CONF_OPTS += --enable-compat LIBPTHSEM_CONFIG_SCRIPTS += pth-config -- 2.30.2