On Mon 31-07-17 11:56:24, Mike Kravetz wrote: > If hugetlb pages are requested in mmap or shmget system calls, a huge > page size other than default can be requested. This is accomplished by > encoding the log2 of the huge page size in the upper bits of the flag > argument. asm-generic and arch specific headers all define the same > values for these encodings. > > Put common definitions in a single header file. The primary uapi > header files for mmap and shm will use these definitions as a basis > for definitions specific to those system calls. > > Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> > --- > include/uapi/asm-generic/hugetlb_encode.h | 34 +++++++++++++++++++++++++++++++ > 1 file changed, 34 insertions(+) > create mode 100644 include/uapi/asm-generic/hugetlb_encode.h > > diff --git a/include/uapi/asm-generic/hugetlb_encode.h b/include/uapi/asm-generic/hugetlb_encode.h > new file mode 100644 > index 0000000..e4732d3 > --- /dev/null > +++ b/include/uapi/asm-generic/hugetlb_encode.h > @@ -0,0 +1,34 @@ > +#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_256MB (28 << 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_ */ > -- > 2.7.5 -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
