[Qemu-devel] [PATCHv2] Add compat eventfd header

["Michael S. Tsirkin" <mst@redhat.com>]

Support build on rhel 5.X where we have syscall for eventfd but not
userspace wrapper.

(cherry-picked from commit 9e3269181e9bc56feb43bcd4e8ce0b82cd543e65
 in qemu-kvm.git).

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Changes from v1:
  checkpatch fix
  address comments by agraf
  verify we are on linux

 compat/sys/eventfd.h |   20 ++++++++++++++++++++
 configure            |    6 ++++--
 2 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 compat/sys/eventfd.h

diff --git a/compat/sys/eventfd.h b/compat/sys/eventfd.h
new file mode 100644
index 0000000..1801a5f
--- /dev/null
+++ b/compat/sys/eventfd.h
@@ -0,0 +1,20 @@
+#ifndef _COMPAT_SYS_EVENTFD
+#define _COMPAT_SYS_EVENTFD
+
+#ifdef CONFIG_EVENTFD
+
+#ifndef __linux__
+#error __linux__ is not defined: eventfd is only supported on linux
+#endif
+
+#include <unistd.h>
+#include <syscall.h>
+
+static inline int eventfd(int count, int flags)
+{
+    return syscall(SYS_eventfd, count, flags);
+}
+
+#endif
+
+#endif
diff --git a/configure b/configure
index 856b41e..6f7dd74 100755
--- a/configure
+++ b/configure
@@ -822,7 +822,6 @@ esac
 
 [ -z "$guest_base" ] && guest_base="$host_guest_base"
 
-
 default_target_list=""
 
 # these targets are portable
@@ -891,6 +890,9 @@ sparc64-bsd-user \
 "
 fi
 
+#compat headers
+QEMU_CFLAGS="$QEMU_CFLAGS -idirafter $source_path/compat"
+
 if test x"$show_help" = x"yes" ; then
 cat << EOF
 
@@ -2122,7 +2124,7 @@ int main(void)
     return 0;
 }
 EOF
-if compile_prog "" "" ; then
+if compile_prog "-DCONFIG_EVENTFD" "" ; then
   eventfd=yes
 fi
 
-- 
1.7.5.53.gc233e