include/uapi/asm-generic/hugetlb_encode.h

Source file repositories/reference/linux-study-clean/include/uapi/asm-generic/hugetlb_encode.h

File Facts

System
Linux kernel
Corpus path
include/uapi/asm-generic/hugetlb_encode.h
Extension
.h
Size
1820 bytes
Lines
38
Domain
Repository Root And Misc
Bucket
include
Inferred role
Repository Root And Misc: implementation source
Status
source implementation candidate

Why This File Exists

Top-level or miscellaneous repository surface. Use this as map coverage unless a later manual pass promotes the file into a deeper subsystem dossier.

Dependency Surface

Detected Declarations

Annotated Snippet

#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_16KB	(14U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_64KB	(16U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_512KB	(19U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_1MB		(20U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_2MB		(21U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_8MB		(23U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_16MB	(24U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_32MB	(25U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_256MB	(28U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_512MB	(29U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_1GB		(30U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_2GB		(31U << HUGETLB_FLAG_ENCODE_SHIFT)
#define HUGETLB_FLAG_ENCODE_16GB	(34U << HUGETLB_FLAG_ENCODE_SHIFT)

#endif /* _ASM_GENERIC_HUGETLB_ENCODE_H_ */

Annotation

Implementation Notes