root/include/asm-x86/sparsemem.h

INCLUDED FROM

#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
#endif

#endif /* CONFIG_SPARSEMEM */
#endif /* ASM_X86__SPARSEMEM_H */