x86: convert cpu_to_apicid to be a per cpu variable

This patch converts the x86_cpu_to_apicid array to be a per cpu
variable. This saves sizeof(apicid) * NR unused cpus.  Access is mostly
from startup and CPU HOTPLUG functions.

MP_processor_info() is one of the functions that require access to the
x86_cpu_to_apicid array before the per_cpu data area is setup.  For this
case, a pointer to the __initdata array is initialized in setup_arch()
and removed in smp_prepare_cpus() after the per_cpu data area is
initialized.

A second change is included to change the initial array value of ARCH
i386 from 0xff to BAD_APICID to be consistent with ARCH x86_64.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/asm-x86/smp_64.h b/include/asm-x86/smp_64.h
index 9d35018e54fe..f1545704e24e 100644
--- a/include/asm-x86/smp_64.h
+++ b/include/asm-x86/smp_64.h
@@ -86,7 +86,9 @@ static inline int hard_smp_processor_id(void)
  * Some lowlevel functions might want to know about
  * the real APIC ID <-> CPU # mapping.
  */
-extern u8 x86_cpu_to_apicid[NR_CPUS];   /* physical ID */
+extern u8 __initdata x86_cpu_to_apicid_init[];
+extern void *x86_cpu_to_apicid_ptr;
+DECLARE_PER_CPU(u8, x86_cpu_to_apicid); /* physical ID */
 extern u8 bios_cpu_apicid[];
 
 static inline int cpu_present_to_apicid(int mps_cpu)
@@ -117,7 +119,7 @@ static __inline int logical_smp_processor_id(void)
 }
 
 #ifdef CONFIG_SMP
-#define cpu_physical_id(cpu)            x86_cpu_to_apicid[cpu]
+#define cpu_physical_id(cpu)            per_cpu(x86_cpu_to_apicid, cpu)
 #else
 #define cpu_physical_id(cpu)            boot_cpu_id
 #endif /* !CONFIG_SMP */