[Qemu-devel] [PATCH] w32: Fix build with older gcc (unresolved symbol)

[Stefan Weil <sw@weilnetz.de>]

The cross i586-mingw32msvc-gcc 4.4.4 from Debian Squeeze does not support
__sync_val_compare_and_swap by default.

Using -march=i686 fixes that and should also result in better code.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
---

Maybe this modification is also needed for native gcc-4.4 and older
on Linux i386. If yes, we can move the new script code out of the
MinGW conditional code.

Newer versions of gcc obviously use -march=i686 by default and
don't need the patch, but it also won't do any harm for those
versions.

Stefan


 configure |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/configure b/configure
index f2af714..70c2219 100755
--- a/configure
+++ b/configure
@@ -562,6 +562,11 @@ if test "$mingw32" = "yes" ; then
   QEMU_CFLAGS="-DWIN32_LEAN_AND_MEAN -DWINVER=0x501 $QEMU_CFLAGS"
   # enable C99/POSIX format strings (needs mingw32-runtime 3.15 or later)
   QEMU_CFLAGS="-D__USE_MINGW_ANSI_STDIO=1 $QEMU_CFLAGS"
+  if test "$cpu" = "i386"; then
+    # We need something better than i386 for __sync_val_compare_and_swap
+    # and can expect that QEMU will only run on i686 or later.
+    QEMU_CFLAGS="-march=i686 $QEMU_CFLAGS"
+  fi
   LIBS="-lwinmm -lws2_32 -liphlpapi $LIBS"
 cat > $TMPC << EOF
 int main(void) { return 0; }
-- 
1.7.10.4