Since they're being passed to Dom0 using an array of uint32_t, they
must be representable as 32-bit quantities, and hence the buffer
allocation must specify an upper address boundary.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- 2010-06-15.orig/xen/common/trace.c	2010-06-28 11:58:37.000000000 +0200
+++ 2010-06-15/xen/common/trace.c	2010-06-28 12:16:05.000000000 +0200
@@ -130,7 +130,8 @@ static int alloc_trace_bufs(void)
         char         *rawbuf;
         struct t_buf *buf;
 
-        if ( (rawbuf = alloc_xenheap_pages(order, 0)) == NULL )
+        if ( (rawbuf = alloc_xenheap_pages(
+                order, MEMF_bits(32 + PAGE_SHIFT))) == NULL )
         {
             printk("Xen trace buffers: memory allocation failed\n");
             opt_tbuf_size = 0;