[PATCH 5/5] kexec: X86: Pass memory ranges via e820 table instead of memmap= boot parameter

[H. Peter Anvin]

On 04/12/2013 07:31 AM, Vivek Goyal wrote:
>>
>> I also have to admit that I don't see the difference between /dev/mem
>> and /dev/oldmem, as the former allows access to memory ranges outside
>> the ones used by the current kernel, which is what the oldmem device
>> seems to be intended to od.
> 
> I think one difference seems to be that /dev/mem assumes that validly
> accessed memory is already mapped in kernel while /dev/oldmeme assumes
> it is not mapped and creates temporary mappings explicitly.
> 

Dave Hansen has been working on fixing /dev/mem for HIGHMEM.

	-hpa