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-rw-r--r--sysdeps/i386/configure.in19
1 files changed, 19 insertions, 0 deletions
diff --git a/sysdeps/i386/configure.in b/sysdeps/i386/configure.in
index 9967a160ba..56a7c1fbcc 100644
--- a/sysdeps/i386/configure.in
+++ b/sysdeps/i386/configure.in
@@ -1,6 +1,25 @@
 GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
 # Local configure fragment for sysdeps/i386.
 
+# The GNU C Library can't be built for i386.  There are several reasons for
+# this restriction.  The primary reason is that i386 lacks the atomic
+# operations required to support the current NPTL implementation.  While it is
+# possible that such atomic operations could be emulated in the kernel to date
+# no such work has been done to enable this.  Even with NPTL disabled you still
+# have no atomic.h implementation.  Given the declining use of i386 we disable
+# support for building with `-march=i386' or `-mcpu=i386.' We don't explicitly
+# check for i386, instead we make sure the compiler has support for inlining
+# the builtin __sync_val_compare_and_swap. If it does then we should have no
+# problem building for i386.
+LIBC_COMPILER_BUILTIN_INLINED(
+  [__sync_val_compare_and_swap],
+  [int a, b, c; __sync_val_compare_and_swap (&a, b, c);],
+  [-O0],
+  [libc_cv_unsupported_i386=no],
+  [AC_MSG_ERROR([
+*** Building with -march=i386/-mcpu=i386 is not supported.
+*** Please use host i786, i686, i586, or i486.])])
+
 AC_CHECK_HEADER([cpuid.h], ,
   [AC_MSG_ERROR([gcc must provide the <cpuid.h> header])],
   [/* No default includes.  */])