--- qemu-0.9.0/exec.c	2007-07-23 13:57:29.000000000 +0200
+++ qemu/exec.c	2007-07-23 13:53:06.000000000 +0200
@@ -1942,9 +1942,11 @@
     cpu_register_io_memory(IO_MEM_NOTDIRTY >> IO_MEM_SHIFT, error_mem_read, notdirty_mem_write, NULL);
     io_mem_nb = 5;
 
-    /* alloc dirty bits array */
-    phys_ram_dirty = qemu_vmalloc(phys_ram_size >> TARGET_PAGE_BITS);
-    memset(phys_ram_dirty, 0xff, phys_ram_size >> TARGET_PAGE_BITS);
+    if (phys_ram_size) {
+    	/* alloc dirty bits array */
+    	phys_ram_dirty = qemu_vmalloc(phys_ram_size >> TARGET_PAGE_BITS);
+    	memset(phys_ram_dirty, 0xff, phys_ram_size >> TARGET_PAGE_BITS);
+    }
 }
 
 /* mem_read and mem_write are arrays of functions containing the