4 files changed, 56 insertions, 12 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 43c527d72f2f..f9ea0803d5d6 100644
--- a/Documentation/kernel-parameters.txt
+++ b/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.
 
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e50e38e76d9f..a0d7406e8b37 100644
--- a/arch/x86/Kconfig
+++ b/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)
diff --git a/arch/x86/kernel/e820_64.c b/arch/x86/kernel/e820_64.c
index 9184e6437c4f..d6ada0833876 100644
--- a/arch/x86/kernel/e820_64.c
+++ b/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;
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 52f54ee4559f..ae225c3ae9a8 100644
--- a/arch/x86/mm/init_64.c
+++ b/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;
 }
 
@@ -501,8 +505,10 @@ static void __init early_memtest(unsigned long start, unsigned long end)
         unsigned long t_start, t_size;
         unsigned pattern;
 
-        if (memtest_pattern)
-                printk(KERN_INFO "early_memtest: pattern num %d", 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;
                 t_size = 0;
@@ -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");
+        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.