powerpc/64s: introduce CONFIG_MAXSMP to test very large SMP

Similarly to x86, add MAXSMP that should help flush out problems with
vary large SMP and other values associated with very big systems.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

arch/powerpc/Kconfig

@@ -64,6 +64,13 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK
 config NEED_PER_CPU_PAGE_FIRST_CHUNK
 	def_bool y if PPC64
 
+config MAXSMP
+	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
+	depends on SMP && DEBUG_KERNEL && PPC_BOOK3S_64
+	help
+	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
+	  If unsure, say N.
+
 config NR_IRQS
 	int "Number of virtual interrupt numbers"
 	range 32 1048576
@@ -668,6 +675,7 @@ config NUMA
 
 config NODES_SHIFT
 	int
+	default "10" if MAXSMP
 	default "8" if PPC64
 	default "4"
 	depends on NUMA

arch/powerpc/platforms/Kconfig.cputype

@@ -476,8 +476,9 @@ config SMP
 	  If you don't know what to do here, say N.
 
 config NR_CPUS
-	int "Maximum number of CPUs (2-8192)" if SMP
-	range 2 8192 if SMP
+	int "Maximum number of CPUs (2-8192)" if SMP && !MAXSMP
+	range 2 16384 if SMP
+	default 16384 if MAXSMP
 	default "1" if !SMP
 	default "32" if PPC64
 	default "4"