x86_64: simplify the memtest parameter setting

use CONFIG_MEMTEST only. if it is set, will have memtest=0 (disabled)

need to have memtest=4 in command line to test more patterns.
Signed-off-by: NYinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/Kconfig

@@ -419,35 +419,19 @@ config PARAVIRT
 
 endif
 
-config MEMTEST_BOOTPARAM
-	bool "Memtest boot parameter"
+config MEMTEST
+	bool "Memtest"
 	depends on X86_64
 	default y
 	help
 	  This option adds a kernel parameter 'memtest', which allows memtest
-	  to be disabled at boot.  If this option is selected, memtest
-	  functionality can be disabled with memtest=0 on the kernel
-	  command line.  The purpose of this option is to allow a single
-	  kernel image to be distributed with memtest built in, but not
-	  necessarily enabled.
-
+	  to be set.
+		memtest=0, mean disabled; -- default
+		memtest=1, mean do 1 test pattern;
+		...
+		memtest=4, mean do 4 test patterns.
 	  If you are unsure how to answer this question, answer Y.
 
-config MEMTEST_BOOTPARAM_VALUE
-	int "Memtest boot parameter default value (0-4)"
-	depends on MEMTEST_BOOTPARAM
-	range 0 4
-	default 0
-	help
-	  This option sets the default value for the kernel parameter
-	  'memtest', which allows memtest to be disabled at boot.  If this
-	  option is set to 0 (zero), the memtest kernel parameter will
-	  default to 0, disabling memtest at bootup.  If this option is
-	  set to 4, the memtest kernel parameter will default to 4,
-	  enabling memtest at bootup, and use that as pattern number.
-
-	  If you are unsure how to answer this question, answer 0.
-
 config ACPI_SRAT
 	def_bool y
 	depends on X86_32 && ACPI && NUMA && (X86_SUMMIT || X86_GENERICARCH)

arch/x86/mm/init_64.c

@@ -431,7 +431,7 @@ static void __init init_gbpages(void)
 		direct_gbpages = 0;
 }
 
-#ifdef CONFIG_MEMTEST_BOOTPARAM
+#ifdef CONFIG_MEMTEST
 
 static void __init memtest(unsigned long start_phys, unsigned long size,
 				 unsigned pattern)
@@ -493,7 +493,8 @@ static void __init memtest(unsigned long start_phys, unsigned long size,
 
 }
 
-static int memtest_pattern __initdata = CONFIG_MEMTEST_BOOTPARAM_VALUE;
+/* default is disabled */
+static int memtest_pattern __initdata;
 
 static int __init parse_memtest(char *arg)
 {