From: Andrei Borzenkov <address@hidden>
Subject: [PATCH] configure: try to force o32 ABI on MIPS

GRUB expects o32 ABI, in particular used assembly is valid only in this mode.
Some systems (e.g. GNU Guix) default to using newer n64 or n32 ABI. Try to
find suitable options to force o32.

For GCC this is simply -mabi=32. While clang supports this option as well,
o32 ABI is valid for MIPS target and n32/64 ABI are valid for MIPS64 target 
only, so use "-target mips -mabi=32".

Reported-By: Mark H Weaver <address@hidden>
Also-By: Mark H Weaver <address@hidden>

---
 configure.ac | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/configure.ac b/configure.ac
index c864311..2e73b3f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -597,6 +597,35 @@ int main (void);
   TARGET_LDFLAGS="$TARGET_LDFLAGS $grub_cv_target_cc_big_endian"
 fi
 
+if test "x$target_cpu" = xmips || test "x$target_cpu" = xmipsel ; then
+  AC_CACHE_CHECK([for options to force MIPS o32 ABI], grub_cv_target_cc_mips_o32_abi, [
+    grub_cv_target_cc_mips_o32_abi=no
+    for arg in "" "-mabi=32" "-target mips -mabi=32" ; do
+      if test x"$grub_cv_target_cc_mips_o32_abi" != xno ; then
+        break
+      fi
+      CFLAGS="$TARGET_CFLAGS $arg -Werror"
+      AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+#if !defined(_ABIO32) || !defined(_MIPS_SIM) || (_MIPS_SIM != _ABIO32)
+#error not o32 ABI
+#endif
+asm (".globl start; start:");
+void __main (void);
+void __main (void) {}
+int main (void);
+]], [[]])],
+		        [grub_cv_target_cc_mips_o32_abi="$arg"], [])
+    done
+  ])
+
+  if test x"$grub_cv_target_cc_mips_o32_abi" = xno ; then
+    AC_MSG_ERROR([could not force MIPS o32 ABI])
+  fi
+
+  TARGET_CFLAGS="$TARGET_CFLAGS $grub_cv_target_cc_mips_o32_abi"
+  TARGET_CCASFLAGS="$TARGET_CCASFLAGS $grub_cv_target_cc_mips_o32_abi"
+fi
+
 AC_CACHE_CHECK([for options to compile assembly], [grub_cv_cc_target_asm_compile], [
 test_program=
 case "x$target_cpu-$platform" in
-- 
tg: (ba218c1..) u/mips-o32 (depends on: master)