x86, apic: Introduce the NOOP apic driver

Introduce NOOP APIC driver. We should use it in case if apic was
disabled due to hardware of software/firmware problems (including
user requested to disable it case).

The driver is attempting to catch any inappropriate apic operation
call with warning issue.

Also it is possible to use some apic operation like IPI calls,
read/write without checking for apic presence which should make
callers code easier.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: yinghai@kernel.org
Cc: macro@linux-mips.org
LKML-Reference: <20091013201022.534682104@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 474d80d3e6cc..08a5f420e07b 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -488,6 +488,8 @@ static inline unsigned int read_apic_id(void)
 
 extern void default_setup_apic_routing(void);
 
+extern struct apic apic_noop;
+
 #ifdef CONFIG_X86_32
 
 extern struct apic apic_default;