Messages in this thread | | | Date | Tue, 12 Nov 2013 05:07:03 +0100 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH 3/3] x86, boot: Change the BIOS corruption checker to scan 640K |
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* H. Peter Anvin <hpa@linux.intel.com> wrote:
> From: "H. Peter Anvin" <hpa@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 <hpa@linux.intel.com> > Cc: Olof Johansson <olof@lixom.net> > Link: http://lkml.kernel.org/r/528168CB.7070602@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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