* H. Peter Anvin <h...@linux.intel.com> wrote:
> From: "H. Peter Anvin" <h...@linux.intel.com>
>
> 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 <h...@linux.intel.com>
> Cc: Olof Johansson <o...@lixom.net>
> Link: http://lkml.kernel.org/r/528168cb.7070...@linux.intel.com
> ---
> 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 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.
I agree with your patches so far, and I'd suggest we go even further: I'd
say the config option is now a misnomer, it should probably be renamed to
CONFIG_X86_FORCE_RESERVE_BIOS_LOW_1MB=y or so.
Btw., should we also force-reserve the remaining bits over 640K..1MB, if
they are not marked as reserved in the memory maps, or do we already
force-reserve them somewhere?
The CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK=y option and the
memory_corruption_check=1 boot option then allow the activation of the low
memory corrupion checker - which debug facility can be used on systems
where someone wants to live dangerously and not reserve the low 1MB of RAM
to the firmware.
Thanks,
Ingo
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