Re: Corrupted low memory in v3.9+

["H. Peter Anvin" <hpa@linux.intel.com>]

On 11/11/2013 03:31 PM, H. Peter Anvin wrote:
> On 11/11/2013 03:35 AM, Ingo Molnar wrote:
> 
> Oops!  I had misunderstood how the checker worked -- I thought it
> checked the *reserved* memory, but it in fact reserves memory
> *independently* and then checks it.
> 

And now I understand why I had that misconception:

> 	  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.

This makes it sound like it scans the low 64K when it is turned on, i.e.
the bit that is reserved by default.

I think we should change that default too to 640K.  I will post a
patchset shortly.

	-hpa