# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1227785092 0
# Node ID 840b761e07c1f8b6146584df320ddbd6bce07fae
# Parent  b1a38832be05156ac993dae1fb53b85b0aa26a1f
x86, hpet: check hpet existence

Add check on hpet existence which is removed accidentally
in previous changeset (18790). Or else BAD PERIOD error can be seen.

Signed-off-by: Kevin Tian <kevin.tian@intel.com>

diff -r b1a38832be05 -r 840b761e07c1 xen/arch/x86/hpet.c
--- a/xen/arch/x86/hpet.c	Thu Nov 27 11:22:38 2008 +0000
+++ b/xen/arch/x86/hpet.c	Thu Nov 27 11:24:52 2008 +0000
@@ -273,6 +273,9 @@ u64 hpet_setup(void)
         return hpet_rate;
     system_reset_latch = system_reset_counter;
 
+    if ( hpet_address == 0 )
+        return 0;
+
     set_fixmap_nocache(FIX_HPET_BASE, hpet_address);
 
     hpet_id = hpet_read32(HPET_ID);