[PATCH] xen: don't bother trying to set cr4

[Jeremy Fitzhardinge <jeremy@goop.org>]

Xen ignores all updates to cr4, and some versions will kill the domain
if you try to change its value.  Just ignore all changes.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Andi Kleen <ak@suse.de>

---
 arch/i386/xen/enlighten.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

===================================================================
--- a/arch/i386/xen/enlighten.c
+++ b/arch/i386/xen/enlighten.c
@@ -625,8 +625,8 @@ static unsigned long xen_read_cr2_direct
 
 static void xen_write_cr4(unsigned long cr4)
 {
-	/* never allow TSC to be disabled */
-	native_write_cr4(cr4 & ~X86_CR4_TSD);
+	/* Just ignore cr4 changes; Xen doesn't allow us to do
+	   anything anyway. */
 }
 
 static unsigned long xen_read_cr3(void)