s390: make MAX_PHYSMEM_BITS configurable

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index fc842c4b..afac5d8 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -537,6 +537,16 @@
 
 source "mm/Kconfig"
 
+config MAX_PHYSMEM_BITS
+	int "Maximum size of supported physical memory in bits (42-53)"
+	range 42 53
+	default "46"
+	help
+	  This option specifies the maximum supported size of physical memory
+	  in bits. Supported is any size between 2^42 (4TB) and 2^53 (8PB).
+	  Increasing the number of bits also increases the kernel image size.
+	  By default 46 bits (64TB) are supported.
+
 config PACK_STACK
 	def_bool y
 	prompt "Pack kernel stack"