From: "H. Peter Anvin" <[email protected]> Change the BIOS corruption checker to scan 640K if enabled. This is the normal amount that we otherwise would reserve with the new default settings; change the Kconfig help message to indicate that this is now intended as a diagnostic tool when one is considering enabling any chunk of low memory.
Signed-off-by: H. Peter Anvin <[email protected]> Cc: Olof Johansson <[email protected]> Link: http://lkml.kernel.org/r/[email protected] --- arch/x86/Kconfig | 25 +++++++++++-------------- arch/x86/kernel/check.c | 10 +++++----- 2 files changed, 16 insertions(+), 19 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 7631122..554aedd 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1384,24 +1384,21 @@ config HIGHPTE config X86_CHECK_BIOS_CORRUPTION bool "Check for low memory corruption" ---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 + 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 reserves and scans the low 640K 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 + It is 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. + you should use the memmap= or reservelow= runtime options or + the CONFIG_X86_RESERVE_LOW compile time option to prevent + the kernel from using that memory. config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK bool "Set the default setting of memory_corruption_check" diff --git a/arch/x86/kernel/check.c b/arch/x86/kernel/check.c index e2dbcb7..c00182d 100644 --- a/arch/x86/kernel/check.c +++ b/arch/x86/kernel/check.c @@ -7,16 +7,16 @@ #include <asm/proto.h> /* - * Some BIOSes seem to corrupt the low 64k of memory during events - * like suspend/resume and unplugging an HDMI cable. Reserve all - * remaining free memory in that area and fill it with a distinct - * pattern. + * Some BIOSes and even some hardware devices seem to corrupt the low + * 640K of memory during events like suspend/resume and unplugging an + * HDMI cable. Reserve all remaining free memory in that area and + * fill it with a distinct pattern. */ #define MAX_SCAN_AREAS 8 static int __read_mostly memory_corruption_check = -1; -static unsigned __read_mostly corruption_check_size = 64*1024; +static unsigned __read_mostly corruption_check_size = 640*1024; static unsigned __read_mostly corruption_check_period = 60; /* seconds */ static struct scan_area { -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
