Extend the maximum addressable memory on x86-64 from 2^44 to
2^46 bytes. This requires some shuffling around of the vmalloc
and virtual memmap memory areas, to keep them away from the
direct mapping of up to 64TB of physical memory.
This patch also introduces a guard hole between the vmalloc
area and the virtual memory map space. There's really no
good reason why we wouldn't have a guard hole there.
[ Impact: future hardware enablement ]
Signed-off-by: Rik van Riel <riel@redhat.com>
LKML-Reference: <20090505172856.6820db22@cuia.bos.redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
on 64-bit x86 the physical memory limit is controlled by the sparsemem
bits - which are 44 bits right now. But MAXMEM (the max pfn number
e820 parsing will allow to enter our sizing routines) is set to
0x00003fffffffffff, i.e. 46 bits - that's too large because it overlaps
into the vmalloc range.
So couple MAXMEM to MAX_PHYSMEM_BITS, and add a comment that the
maximum of MAX_PHYSMEM_BITS is 45 bits.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:
a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
