x86: clean up memory corruption check and add more kernel parameters

The corruption check is enabled in Kconfig by default, but disabled at runtime.

This patch adds several kernel parameters to control the corruption
check's behaviour; these are documented in kernel-parameters.txt.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 23 insertions, 3 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 1bb52e2ca02e..cbee4199689c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -201,9 +201,6 @@ config X86_TRAMPOLINE
         depends on X86_SMP || (X86_VOYAGER && SMP) || (64BIT && ACPI_SLEEP)
         default y
 
-config X86_CHECK_BIOS_CORRUPTION
-        def_bool y
-
 config KTIME_SCALAR
         def_bool X86_32
 source "init/Kconfig"
@@ -1062,6 +1059,29 @@ config HIGHPTE
           low memory.  Setting this option will put user-space page table
           entries in high memory.
 
+config X86_CHECK_BIOS_CORRUPTION
+        bool "Check for low memory corruption"
+        default y
+        help
+         Periodically check for memory corruption in low memory, which
+         is suspected to be caused by BIOS.  Even when enabled in the
+         configuration, it is disabled at runtime.  Enable it by
+         setting "memory_corruption_check=1" on the kernel command
+         line.  By default it scans the low 64k of memory every 60
+         seconds; see the memory_corruption_check_size and
+         memory_corruption_check_period parameters in
+         Documentation/kernel-parameters.txt to adjust this.
+
+         When enabled with the default parameters, this option has
+         almost no overhead, as it reserves a relatively small amount
+         of memory and scans it infrequently.  It both detects corruption
+         and prevents it from affecting the running system.
+
+         It is, however, intended as a diagnostic tool; if repeatable
+         BIOS-originated corruption always affects the same memory,
+         you can use memmap= to prevent the kernel from using that
+         memory.
+
 config MATH_EMULATION
         bool
         prompt "Math emulation" if X86_32