linux/include/uapi/asm-generic/hugetlb_encode.h

#ifndef _ASM_GENERIC_HUGETLB_ENCODE_H_
#define _ASM_GENERIC_HUGETLB_ENCODE_H_

/*
 * Several system calls take a flag to request "hugetlb" huge pages.
 * Without further specification, these system calls will use the
 * system's default huge page size.  If a system supports multiple
 * huge page sizes, the desired huge page size can be specified in
 * bits [26:31] of the flag arguments.  The value in these 6 bits
 * will encode the log2 of the huge page size.
 *
 * The following definitions are associated with this huge page size
 * encoding in flag arguments.  System call specific header files
 * that use this encoding should include this file.  They can then
 * provide definitions based on these with their own specific prefix.
 * for example:
 * #define MAP_HUGE_SHIFT HUGETLB_FLAG_ENCODE_SHIFT
 */

#define HUGETLB_FLAG_ENCODE_SHIFT	26
#define HUGETLB_FLAG_ENCODE_MASK	0x3f

#define HUGETLB_FLAG_ENCODE_64KB	(16 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_512KB	(19 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_1MB		(20 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_2MB		(21 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_8MB		(23 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_16MB	(24 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_32MB	(25 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_256MB	(28 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_512MB	(29 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_1GB		(30 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_2GB		(31 << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_16GB	(34 << HUGETLB_FLAG_ENCODE_SHIFT)

#endif /* _ASM_GENERIC_HUGETLB_ENCODE_H_ */