[IA64] Count disabled cpus as potential hot-pluggable CPUs

Have a facility to account for potentially hot-pluggable CPUs. ACPI doesnt
give a determinstic method to find hot-pluggable CPUs. Hence we use 2 methods
to assist.

- BIOS can mark potentially hot-pluggable CPUs as disabled in the MADT tables.
- User can specify the number of hot-pluggable CPUs via parameter
  additional_cpus=X

The option is enabled only if ACPI_CONFIG_HOTPLUG_CPU=y which enables the
physical hotplug option. Without which user can still use logical onlining
and offlining of CPUs by enabling CONFIG_HOTPLUG_CPU=y

Adds more bits to cpu_possible_map for potentially hot-pluggable cpus.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/asm-ia64/acpi.h b/include/asm-ia64/acpi.h
index 3a544ffc500..f7a51765430 100644
--- a/include/asm-ia64/acpi.h
+++ b/include/asm-ia64/acpi.h
@@ -106,6 +106,8 @@ extern unsigned int can_cpei_retarget(void);
 extern unsigned int is_cpu_cpei_target(unsigned int cpu);
 extern void set_cpei_target_cpu(unsigned int cpu);
 extern unsigned int get_cpei_target_cpu(void);
+extern void prefill_possible_map(void);
+extern int additional_cpus;
 
 #ifdef CONFIG_ACPI_NUMA
 /* Proximity bitmap length; _PXM is at most 255 (8 bit)*/