[PATCH 1/2] x86 e820: Check for exactmap appearance when parsing first memmap option

[H. Peter Anvin]

On 01/22/2013 07:20 AM, Thomas Renninger wrote:
> From: Yinghai Lu <yinghai at kernel.org>
> 
> memmap=exactmap will throw away all original, but also until then
> user defined (through other provided memmap= parameters) areas.
> That means all memmap= boot parameters passed before a memmap=exactmap
> parameter are not recognized.
> Without this fix:
> memmap=x at y memmap=exactmap memmap=i#k
> only i#k would get recognized.
> 
> This is wrong, this fix will only throw away all original e820 areas once
> when memmap=exactmap is found in the whole boot command line and before
> any other memmap= option is parsed.
> 

I don't understand why this is wrong.  The kernel command line is always
parsed from left to right, and I don't see anything inherently
problematic with that with something like a big hammer like exactmap.

	-hpa