tools/include/asm-generic/hugetlb_encode.h

   1 #ifndef _ASM_GENERIC_HUGETLB_ENCODE_H_
   2 #define _ASM_GENERIC_HUGETLB_ENCODE_H_
   3
   4 /*
   5  * Several system calls take a flag to request "hugetlb" huge pages.
   6  * Without further specification, these system calls will use the
   7  * system's default huge page size.  If a system supports multiple
   8  * huge page sizes, the desired huge page size can be specified in
   9  * bits [26:31] of the flag arguments.  The value in these 6 bits
  10  * will encode the log2 of the huge page size.
  11  *
  12  * The following definitions are associated with this huge page size
  13  * encoding in flag arguments.  System call specific header files
  14  * that use this encoding should include this file.  They can then
  15  * provide definitions based on these with their own specific prefix.
  16  * for example:
  17  * #define MAP_HUGE_SHIFT HUGETLB_FLAG_ENCODE_SHIFT
  18  */
  19
  20 #define HUGETLB_FLAG_ENCODE_SHIFT       26
  21 #define HUGETLB_FLAG_ENCODE_MASK        0x3f
  22
  23 #define HUGETLB_FLAG_ENCODE_64KB        (16 << HUGETLB_FLAG_ENCODE_SHIFT)
  24 #define HUGETLB_FLAG_ENCODE_512KB       (19 << HUGETLB_FLAG_ENCODE_SHIFT)
  25 #define HUGETLB_FLAG_ENCODE_1MB         (20 << HUGETLB_FLAG_ENCODE_SHIFT)
  26 #define HUGETLB_FLAG_ENCODE_2MB         (21 << HUGETLB_FLAG_ENCODE_SHIFT)
  27 #define HUGETLB_FLAG_ENCODE_8MB         (23 << HUGETLB_FLAG_ENCODE_SHIFT)
  28 #define HUGETLB_FLAG_ENCODE_16MB        (24 << HUGETLB_FLAG_ENCODE_SHIFT)
  29 #define HUGETLB_FLAG_ENCODE_256MB       (28 << HUGETLB_FLAG_ENCODE_SHIFT)
  30 #define HUGETLB_FLAG_ENCODE_1GB         (30 << HUGETLB_FLAG_ENCODE_SHIFT)
  31 #define HUGETLB_FLAG_ENCODE_2GB         (31 << HUGETLB_FLAG_ENCODE_SHIFT)
  32 #define HUGETLB_FLAG_ENCODE_16GB        (34 << HUGETLB_FLAG_ENCODE_SHIFT)
  33
  34 #endif /* _ASM_GENERIC_HUGETLB_ENCODE_H_ */