[S390] config option for z9-109 code generation.

Add a kernel config option for the IBM System z9. This will produce
faster code on newer compilers using the -march=z9-109 option.
Signed-off-by: NChristian Borntraeger <cborntra@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/Kconfig

@@ -153,6 +153,14 @@ config MARCH_Z990
 	  This will be slightly faster but does not work on
 	  older machines such as the z900.
 
+config MARCH_Z9_109
+	bool "IBM System z9"
+	help
+	  Select this to enable optimizations for IBM System z9-109, IBM
+	  System z9 Enterprise Class (z9 EC), and IBM System z9 Business
+	  Class (z9 BC). The kernel will be slightly faster but will not
+	  work on older machines such as the z990, z890, z900, and z800.
+
 endchoice
 
 config PACK_STACK

arch/s390/Makefile

@@ -33,6 +33,7 @@ endif
 cflags-$(CONFIG_MARCH_G5)   += $(call cc-option,-march=g5)
 cflags-$(CONFIG_MARCH_Z900) += $(call cc-option,-march=z900)
 cflags-$(CONFIG_MARCH_Z990) += $(call cc-option,-march=z990)
+cflags-$(CONFIG_MARCH_Z9_109) += $(call cc-option,-march=z9-109)
 
 #
 # Prevent tail-call optimizations, to get clearer backtraces: