x86: memtest bootparam

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/kernel-parameters.txt

@@ -1147,6 +1147,11 @@ and is between 256 and 4096 characters. It is defined in the file
 			         or
 			         memmap=0x10000$0x18690000
 
+	memtest=	[KNL,X86_64] Enable memtest
+			Format: <integer>
+			range: 0,4 : pattern number
+			default : 0 <disable>
+
 	meye.*=		[HW] Set MotionEye Camera parameters
 			See Documentation/video4linux/meye.txt.
 

arch/x86/Kconfig

@@ -382,6 +382,35 @@ config PARAVIRT
 
 endif
 
+config MEMTEST_BOOTPARAM
+	bool "Memtest boot parameter"
+	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.
+
+	  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/kernel/e820_64.c

@@ -241,7 +241,9 @@ unsigned long __init find_e820_area(unsigned long start, unsigned long end,
 /*
  * Find next free range after *start
  */
-unsigned long __init find_e820_area_size(unsigned long start, unsigned long *sizep, unsigned long align)
+unsigned long __init find_e820_area_size(unsigned long start,
+					 unsigned long *sizep,
+					 unsigned long align)
 {
 	int i;
 
@@ -254,17 +256,15 @@ unsigned long __init find_e820_area_size(unsigned long start, unsigned long *siz
 			continue;
 		addr = round_up(ei->addr, align);
 		ei_last = ei->addr + ei->size;
-//		printk(KERN_DEBUG "find_e820_area_size : e820 %d [%llx, %lx]\n", i, ei->addr, ei_last);
 		if (addr < start)
 			addr = round_up(start, align);
-//		printk(KERN_DEBUG "find_e820_area_size : 0 [%lx, %lx]\n", addr, ei_last);
 		if (addr >= ei_last)
 			continue;
 		*sizep = ei_last - addr;
-		while (bad_addr_size(&addr, sizep, align) && addr+ *sizep <= ei_last)
+		while (bad_addr_size(&addr, sizep, align) &&
+			addr + *sizep <= ei_last)
 			;
 		last = addr + *sizep;
-//		printk(KERN_DEBUG "find_e820_area_size : 1 [%lx, %lx]\n", addr, last);
 		if (last > ei_last)
 			continue;
 		return addr;

arch/x86/mm/init_64.c

@@ -427,7 +427,10 @@ static void __init init_gbpages(void)
 		direct_gbpages = 0;
 }
 
-static void __init memtest(unsigned long start_phys, unsigned long size, unsigned pattern)
+#ifdef CONFIG_MEMTEST_BOOTPARAM
+
+static void __init memtest(unsigned long start_phys, unsigned long size,
+				 unsigned pattern)
 {
 	unsigned long i;
 	unsigned long *start;
@@ -486,11 +489,12 @@ static void __init memtest(unsigned long start_phys, unsigned long size, unsigne
 
 }
 
-static int __initdata memtest_pattern;
+static int memtest_pattern __initdata = CONFIG_MEMTEST_BOOTPARAM_VALUE;
+
 static int __init parse_memtest(char *arg)
 {
 	if (arg)
-		memtest_pattern = simple_strtoul(arg, NULL, 0) + 1;
+		memtest_pattern = simple_strtoul(arg, NULL, 0);
 	return 0;
 }
 
@@ -501,7 +505,9 @@ static void __init early_memtest(unsigned long start, unsigned long end)
 	unsigned long t_start, t_size;
 	unsigned pattern;
 
-	if (memtest_pattern)
+	if (!memtest_pattern)
+		return;
+
 	printk(KERN_INFO "early_memtest: pattern num %d", memtest_pattern);
 	for (pattern = 0; pattern < memtest_pattern; pattern++) {
 		t_start = start;
@@ -523,9 +529,13 @@ static void __init early_memtest(unsigned long start, unsigned long end)
 			t_start += t_size;
 		}
 	}
-	if (memtest_pattern)
 	printk(KERN_CONT "\n");
 }
+#else
+static void __init early_memtest(unsigned long start, unsigned long end)
+{
+}
+#endif
 
 /*
  * Setup the direct mapping of the physical memory at PAGE_OFFSET.