Linux中数据类型

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

#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_HIGHMEM64Gtypedef u64 dma_addr_t;#elsetypedef u32 dma_addr_t;#endiftypedef u64 dma64_addr_t;#ifdef CONFIG_LBDtypedef u64 sector_t;#define HAVE_SECTOR_T#endiftypedef 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_NAMEStypedef __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 */#elsetypedef __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_Ttypedef __kernel_size_t        size_t;#endif#ifndef _SSIZE_T#define _SSIZE_Ttypedef __kernel_ssize_t    ssize_t;#endif#ifndef _PTRDIFF_T#define _PTRDIFF_Ttypedef __kernel_ptrdiff_t    ptrdiff_t;#endif#ifndef _TIME_T#define _TIME_Ttypedef __kernel_time_t        time_t;#endif#ifndef _CLOCK_T#define _CLOCK_Ttypedef __kernel_clock_t    clock_t;#endif#ifndef _CADDR_T#define _CADDR_Ttypedef __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_Ttypedef 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#endiftypedef __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 */