diff -r 5b92eed96bd3 drivers/xen/privcmd/privcmd.c
--- a/drivers/xen/privcmd/privcmd.c	Tue Sep 18 10:08:36 2007 +0100
+++ b/drivers/xen/privcmd/privcmd.c	Tue Sep 18 10:21:42 2007 +0100
@@ -69,7 +69,25 @@ static long privcmd_ioctl(struct file *f
 			"popl %%ecx; popl %%ebx"
 			: "=a" (ret) : "0" (&hypercall) : "memory" );
 #elif defined (__x86_64__)
-		if (hypercall.op < (PAGE_SIZE >> 5)) {
+		if (hypercall.op >= (PAGE_SIZE >> 5))
+			break;
+
+		if (test_tsk_thread_flag(current, TIF_IA32)) {
+			__asm__ __volatile__ (
+			"pushq %%rbx; pushq %%rcx; pushq %%rdx; "
+			"pushq %%rsi; pushq %%rdi; pushq %%rbp; "
+			"xorq %%rbp,%%rbp ;"
+			"movl  8(%%rax),%%ebx ;"
+			"movl 16(%%rax),%%ecx ;"
+			"movl 24(%%rax),%%edx ;"
+			"movl 32(%%rax),%%esi ;"
+			"movl 40(%%rax),%%edi ;"
+			"movl   (%%rax),%%eax ;"
+			"int  $0x83;"
+			"popq %%rbp; popq %%rdi; popq %%rsi; popq %%rdx; "
+			"popq %%rcx; popq %%rbx"
+			: "=a" (ret) : "0" (&hypercall) : "memory" );
+		} else {
 			long ign1, ign2, ign3;
 			__asm__ __volatile__ (
 				"movq %8,%%r10; movq %9,%%r8;"