linux/arch/x86/include/asm/sparsemem.h
Ingo Molnar b6fd6f2673 x86, mm: limit MAXMEM on 64-bit
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>
2008-12-16 19:31:52 +01:00

34 lines
920 B
C

#ifndef _ASM_X86_SPARSEMEM_H
#define _ASM_X86_SPARSEMEM_H
#ifdef CONFIG_SPARSEMEM
/*
* generic non-linear memory support:
*
* 1) we will not split memory into more chunks than will fit into the flags
* field of the struct page
*
* SECTION_SIZE_BITS 2^n: size of each section
* MAX_PHYSADDR_BITS 2^n: max size of physical address space
* MAX_PHYSMEM_BITS 2^n: how much memory we can have in that space
*
*/
#ifdef CONFIG_X86_32
# ifdef CONFIG_X86_PAE
# define SECTION_SIZE_BITS 29
# define MAX_PHYSADDR_BITS 36
# define MAX_PHYSMEM_BITS 36
# else
# define SECTION_SIZE_BITS 26
# define MAX_PHYSADDR_BITS 32
# define MAX_PHYSMEM_BITS 32
# endif
#else /* CONFIG_X86_32 */
# define SECTION_SIZE_BITS 27 /* matt - 128 is convenient right now */
# define MAX_PHYSADDR_BITS 44
# define MAX_PHYSMEM_BITS 44 /* Can be max 45 bits */
#endif
#endif /* CONFIG_SPARSEMEM */
#endif /* _ASM_X86_SPARSEMEM_H */