1GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
2# Local configure fragment for sysdeps/i386.
3
4# We no longer support i386 since it lacks the atomic instructions
5# required to implement NPTL threading.
6if test "$config_machine" = i386; then
7  AC_MSG_ERROR([
8*** ERROR: Support for i386 is deprecated.
9*** Please use host i786, i686, i585 or i486.
10*** For example: /src/glibc/configure --host=i686-pc-linux-gnu ..."])
11fi
12
13# The GNU C Library can't be built for i386.  There are several reasons for
14# this restriction.  The primary reason is that i386 lacks the atomic
15# operations required to support the current NPTL implementation.  While it is
16# possible that such atomic operations could be emulated in the kernel to date
17# no such work has been done to enable this.  Even with NPTL disabled you still
18# have no atomic.h implementation.  Given the declining use of i386 we disable
19# support for building with `-march=i386' or `-mcpu=i386.' We don't explicitly
20# check for i386, instead we make sure the compiler has support for inlining
21# the builtin __sync_val_compare_and_swap. If it does then we should have no
22# problem building for i386.
23LIBC_COMPILER_BUILTIN_INLINED(
24  [__sync_val_compare_and_swap],
25  [int a, b, c; __sync_val_compare_and_swap (&a, b, c);],
26  [-O0],
27  [libc_cv_unsupported_i386=no],
28  [AC_MSG_ERROR([
29*** Building with -march=i386/-mcpu=i386 is not supported.
30*** Please use host i786, i686, i586, or i486.
31*** For example: /source/glibc/configure CFLAGS='-O2 -march=i686' ...])])
32
33dnl Check if linker can convert "movl main@GOT(%ebx), %eax" to
34dnl "leal main@GOTOFF(%ebx), %eax" for static PIE.
35if test "$static_pie" = yes; then
36  AC_CACHE_CHECK(for linker static PIE support, libc_cv_ld_static_pie, [dnl
37cat > conftest.s <<\EOF
38	.text
39	.global _start
40_start:
41	movl	_start@GOT(%ebx), %eax
42EOF
43  libc_cv_pie_option="-Wl,-pie"
44  libc_cv_ld_static_pie=no
45  if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostartfiles -nostdlib $no_ssp $libc_cv_pie_option -o conftest conftest.s 1>&AS_MESSAGE_LOG_FD); then
46    if $READELF -r conftest | grep 'There are no relocations in this file.' > /dev/null; then
47      libc_cv_ld_static_pie=yes
48    fi
49  fi
50rm -f conftest*])
51  if test "$libc_cv_ld_static_pie" != yes; then
52    AC_MSG_ERROR([linker support for static PIE needed])
53  fi
54fi
55
56dnl When multi-arch is enabled, all external functions must be called
57dnl via PIC PLT in PIE, which requires setting up EBX register.
58if test x"$multi_arch" != xno; then
59  AC_DEFINE(NO_HIDDEN_EXTERN_FUNC_IN_PIE)
60fi
61