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当Linux内核在体系结构差异较大的平台之间移植时，会产生与数据类型相关的问题。
.在编译内核时使用 -Wall -W strict-prototypes 选项, 可以避免很多错误的发生
.内核使用的基本数据类型主要有:
int 标准C语言整数类型
u32 32位整数类型
pid_t 特定内核对象pid的类型
.在不同的CPU体系结构上，C语言的数据类型所占空间不一样。
| arch | char | short | int | long | ptr | long-long | u8 | u16 | u32 | u64 |
| i686 | 1 | 2 | 4 | 4 | 4 | 8 | 1 | 2 | 4 | 8 |
| i386 | 1 | 2 | 4 | 4 | 4 | 8 | 1 | 2 | 4 | 8 |
| alpha | 1 | 2 | 4 | 8 | 8 | 8 | 1 | 2 | 4 | 8 |
| armv41 | 1 | 2 | 4 | 4 | 4 | 8 | 1 | 2 | 4 | 8 |
| ia64 | 1 | 2 | 4 | 8 | 8 | 8 | 1 | 2 | 4 | 8 |
| m68k | 1 | 2 | 4 | 4 | 4 | 8 | 1 | 2 | 4 | 8 |
| mips | 1 | 2 | 4 | 4 | 4 | 8 | 1 | 2 | 4 | 8 |
| ppc | 1 | 2 | 4 | 4 | 4 | 8 | 1 | 2 | 4 | 8 |
| sparc | 1 | 2 | 4 | 4 | 4 | 8 | 1 | 2 | 4 | 8 |
| sparc64 | 1 | 2 | 4 | 4 | 4 | 8 | 1 | 2 | 4 | 8 |
.内核中的地址是unsigned long类型， 指针大小和long类型相同
.内核提供下列数据类型， 所有类型在头文件<asm/types.h>中声明， 这个文件又被头文件<Linux/types.h>所包含， 下面是 include/asm/typs.h文件
[File] /usr/src/kernels/2.6.9-22.EL-i686/include/asm-i386/types.h
#ifndef _I386_TYPES_H
#define _I386_TYPES_H
#ifndef __ASSEMBLY__
typedef unsigned short umode_t;
/*
* __xx is ok: it doesn’t pollute the POSIX namespace. Use these in the
* header files exported to user space
*/
typedef __signed__ char __s8;
typedef unsigned char __u8;
typedef __signed__ short __s16;
typedef unsigned short __u16;
typedef __signed__ int __s32;
typedef unsigned int __u32;
#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
typedef __signed__ long long __s64;
typedef unsigned long long __u64;
#endif
#endif /* __ASSEMBLY__ */
/*
* These aren’t exported outside the kernel to avoid name space clashes
*/
#ifdef __KERNEL__
#define BITS_PER_LONG 32
#ifndef __ASSEMBLY__
#include <linux/config.h>
typedef signed char s8;
typedef unsigned char u8;
typedef signed short s16;
typedef unsigned short u16;
typedef signed int s32;
typedef unsigned int u32;
typedef signed long long s64;
typedef unsigned long long u64;
/* DMA addresses come in generic and 64-bit flavours. */
#ifdef CONFIG_HIGHMEM64G
typedef u64 dma_addr_t;
#else
typedef u32 dma_addr_t;
#endif
typedef u64 dma64_addr_t;
#ifdef CONFIG_LBD
typedef u64 sector_t;
#define HAVE_SECTOR_T
#endif
typedef unsigned short kmem_bufctl_t;
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif
[File] /usr/src/kernels/2.6.9-22.EL-i686/include/linux/types.h
#ifndef _LINUX_TYPES_H
#define _LINUX_TYPES_H
#ifdef __KERNEL__
#include <linux/config.h>
#define BITS_TO_LONGS(bits) \
(((bits)+BITS_PER_LONG-1)/BITS_PER_LONG)
#define DECLARE_BITMAP(name,bits) \
unsigned long name[BITS_TO_LONGS(bits)]
#endif
#include <linux/posix_types.h>
#include <asm/types.h>
#ifndef __KERNEL_STRICT_NAMES
typedef __u32 __kernel_dev_t;
typedef __kernel_fd_set fd_set;
typedef __kernel_dev_t dev_t;
typedef __kernel_ino_t ino_t;
typedef __kernel_mode_t mode_t;
typedef __kernel_nlink_t nlink_t;
typedef __kernel_off_t off_t;
typedef __kernel_pid_t pid_t;
typedef __kernel_daddr_t daddr_t;
typedef __kernel_key_t key_t;
typedef __kernel_SUSEconds_t suseconds_t;
typedef __kernel_timer_t timer_t;
typedef __kernel_clockid_t clockid_t;
typedef __kernel_mqd_t mqd_t;
#ifdef __KERNEL__
typedef __kernel_uid32_t uid_t;
typedef __kernel_gid32_t gid_t;
typedef __kernel_uid16_t uid16_t;
typedef __kernel_gid16_t gid16_t;
#ifdef CONFIG_UID16
/* This is defined by include/asm-{arch}/posix_types.h */
typedef __kernel_old_uid_t old_uid_t;
typedef __kernel_old_gid_t old_gid_t;
#endif /* CONFIG_UID16 */
/* libc5 includes this file to define uid_t, thus uid_t can never change
* when it is included by non-kernel code
*/
#else
typedef __kernel_uid_t uid_t;
typedef __kernel_gid_t gid_t;
#endif /* __KERNEL__ */
#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
typedef __kernel_loff_t loff_t;
#endif
/*
* The following typedefs are also protected by individual ifdefs for
* historical reasons:
*/
#ifndef _SIZE_T
#define _SIZE_T
typedef __kernel_size_t size_t;
#endif
#ifndef _SSIZE_T
#define _SSIZE_T
typedef __kernel_ssize_t ssize_t;
#endif
#ifndef _PTRDIFF_T
#define _PTRDIFF_T
typedef __kernel_ptrdiff_t ptrdiff_t;
#endif
#ifndef _TIME_T
#define _TIME_T
typedef __kernel_time_t time_t;
#endif
#ifndef _CLOCK_T
#define _CLOCK_T
typedef __kernel_clock_t clock_t;
#endif
#ifndef _CADDR_T
#define _CADDR_T
typedef __kernel_caddr_t caddr_t;
#endif
/* bsd */
typedef unsigned char u_char;
typedef unsigned short u_short;
typedef unsigned int u_int;
typedef unsigned long u_long;
/* sysv */
typedef unsigned char unchar;
typedef unsigned short ushort;
typedef unsigned int uint;
typedef unsigned long ulong;
#ifndef __BIT_TYPES_DEFINED__
#define __BIT_TYPES_DEFINED__
typedef __u8 u_int8_t;
typedef __s8 int8_t;
typedef __u16 u_int16_t;
typedef __s16 int16_t;
typedef __u32 u_int32_t;
typedef __s32 int32_t;
#endif /* !(__BIT_TYPES_DEFINED__) */
typedef __u8 uint8_t;
typedef __u16 uint16_t;
typedef __u32 uint32_t;
#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
typedef __u64 uint64_t;
typedef __u64 u_int64_t;
typedef __s64 int64_t;
#endif
/*
* The type used for indexing onto a disc or disc partition.
* If required, asm/types.h can override it and define
* HAVE_SECTOR_T
*/
#ifndef HAVE_SECTOR_T
typedef unsigned long sector_t;
#endif
/*
* The type of an index into the pagecache. Use a #define so asm/types.h
* can override it.
*/
#ifndef pgoff_t
#define pgoff_t unsigned long
#endif
#ifdef __CHECKER__
#define __bitwise __attribute__((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;
#endif /* __KERNEL_STRICT_NAMES */
/*
* Below are truly Linux-specific types that should never collide with
* any application/library that wants linux/types.h.
*/
struct ustat {
__kernel_daddr_t f_tfree;
__kernel_ino_t f_tinode;
char f_fname[6];
char f_fpack[6];
};
#endif /* _LINUX_TYPES_H */
