x86: x2apic, IR: Clean up panic() with nox2apic boot option

Instead of panic() ignore the "nox2apic" boot option when BIOS
has already enabled x2apic prior to OS handover.

[ Impact: printk warning instead of panic() when BIOS has enabled x2apic already ]

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: dwmw2@infradead.org
Cc: Weidong Han <weidong.han@intel.com>
LKML-Reference: <20090420200450.425091000@linux-os.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 2b30e520dce3..d32f5589f1dd 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -141,8 +141,12 @@ static int x2apic_preenabled;
 static int disable_x2apic;
 static __init int setup_nox2apic(char *str)
 {
-        if (x2apic_enabled())
-                panic("Bios already enabled x2apic, can't enforce nox2apic");
+        if (x2apic_enabled()) {
+                pr_warning("Bios already enabled x2apic, "
+                           "can't enforce nox2apic");
+                return 0;
+        }
+
         disable_x2apic = 1;
         setup_clear_cpu_cap(X86_FEATURE_X2APIC);
         return 0;