Index: vl.c
===================================================================
--- vl.c	(revision 5300)
+++ vl.c	(working copy)
@@ -5439,12 +5439,13 @@
     int max_devs;
     int index;
     int cache;
+    int sync;
     int bdrv_flags;
     char *str = arg->opt;
     static const char * const params[] = { "bus", "unit", "if", "index",
                                            "cyls", "heads", "secs", "trans",
                                            "media", "snapshot", "file",
-                                           "cache", "format", NULL };
+                                           "cache", "format", "sync", NULL };
 
     if (check_params(buf, sizeof(buf), params, str) < 0) {
          fprintf(stderr, "qemu: unknown parameter '%s' in '%s'\n",
@@ -5459,6 +5460,7 @@
     translation = BIOS_ATA_TRANSLATION_AUTO;
     index = -1;
     cache = 1;
+    sync = 0;
 
     if (!strcmp(machine->name, "realview") ||
         !strcmp(machine->name, "SS-5") ||
@@ -5612,6 +5614,17 @@
         }
     }
 
+    if (get_param_value(buf, sizeof(buf), "sync", str)) {
+        if (!strcmp(buf, "off"))
+            sync = 0;
+        else if (!strcmp(buf, "on"))
+            sync = 1;
+        else {
+           fprintf(stderr, "qemu: invalid sync option\n");
+           return -1;
+        }
+    }
+
     if (get_param_value(buf, sizeof(buf), "format", str)) {
        if (strcmp(buf, "?") == 0) {
             fprintf(stderr, "qemu: Supported formats:");
@@ -5728,6 +5741,8 @@
         bdrv_flags |= BDRV_O_SNAPSHOT;
     if (!cache)
         bdrv_flags |= BDRV_O_DIRECT;
+    if (sync)
+        bdrv_flags |= BDRV_O_SYNC;
     if (bdrv_open2(bdrv, file, bdrv_flags, drv) < 0 || qemu_key_check(bdrv, file)) {
         fprintf(stderr, "qemu: could not open disk image %s\n",
                         file);
Index: block-raw-posix.c
===================================================================
--- block-raw-posix.c	(revision 5304)
+++ block-raw-posix.c	(working copy)
@@ -127,6 +127,8 @@
     if (flags & BDRV_O_DIRECT)
         open_flags |= O_DIRECT;
 #endif
+    if (flags & BDRV_O_SYNC)
+        open_flags |= O_SYNC;
 
     s->type = FTYPE_FILE;
 
@@ -937,6 +939,8 @@
     if (flags & BDRV_O_DIRECT)
         open_flags |= O_DIRECT;
 #endif
+    if (flags & BDRV_O_SYNC)
+        open_flags |= O_SYNC;
 
     s->type = FTYPE_FILE;
 #if defined(__linux__)
Index: block.h
===================================================================
--- block.h	(revision 5300)
+++ block.h	(working copy)
@@ -48,6 +48,7 @@
                                      it (default for
                                      bdrv_file_open()) */
 #define BDRV_O_DIRECT      0x0020
+#define BDRV_O_SYNC        0x0040
 
 void bdrv_info(void);
 void bdrv_info_stats(void);