1. 根目录:
2. include
3. uapi
4. linux
5. types.h

#ifndef _UAPI_LINUX_TYPES_H
#define _UAPI_LINUX_TYPES_H

#include <asm/types.h>

#ifndef __ASSEMBLY__
#ifndef	__KERNEL__
#ifndef __EXPORTED_HEADERS__
#warning "Attempt to use kernel headers from user space, see http://kernelnewbies.org/KernelHeaders"
#endif /* __EXPORTED_HEADERS__ */
#endif

#include <linux/posix_types.h>


/*
 * Below are truly Linux-specific types that should never collide with
 * any application/library that wants linux/types.h.
 */

#ifdef __CHECKER__
#define __bitwise__ __attribute__((bitwise))
#else
#define __bitwise__
#endif
#ifdef __CHECK_ENDIAN__
#define __bitwise __bitwise__
#else
#define __bitwise
#endif

typedef __u16 __bitwise __le16;
typedef __u16 __bitwise __be16;
typedef __u32 __bitwise __le32;
typedef __u32 __bitwise __be32;
typedef __u64 __bitwise __le64;
typedef __u64 __bitwise __be64;

typedef __u16 __bitwise __sum16;
typedef __u32 __bitwise __wsum;

/*
 * aligned_u64 should be used in defining kernel<->userspace ABIs to avoid
 * common 32/64-bit compat problems.
 * 64-bit values align to 4-byte boundaries on x86_32 (and possibly other
 * architectures) and to 8-byte boundaries on 64-bit architectures.  The new
 * aligned_64 type enforces 8-byte alignment so that structs containing
 * aligned_64 values have the same alignment on 32-bit and 64-bit architectures.
 * No conversions are necessary between 32-bit user-space and a 64-bit kernel.
 */
#define __aligned_u64 __u64 __attribute__((aligned(8)))
#define __aligned_be64 __be64 __attribute__((aligned(8)))
#define __aligned_le64 __le64 __attribute__((aligned(8)))

#endif /*  __ASSEMBLY__ */
#endif /* _UAPI_LINUX_TYPES_H */