1. 定义一个MACH
LINUX中MACHINE定义是用MACHINE_START()/MACHINE_END两个宏来实现的，比如MSM的实现（arch/arm/mach-msm/board-halibut.c）：
MACHINE_START(HALIBUT,"Halibut Board (QCT SURF7200A)") .boot_params = 0x10000100, .map_io = halibut_map_io, .init_irq = halibut_init_irq, .init_machine = halibut_init, .timer = &msm_timer, MACHINE_END
2. MACHINE_START / MACHINE_END定义
上面的定义中，用到了这两个宏MACHINE_START/MACHINE_END，下面是它们具体的定义（在arch/arm/include/asm/mach/arch.h中）：
#defineMACHINE_START(_type,_name) \ static const structmachine_desc __mach_desc_##_type \ __used \ __attribute__((__section__(".arch.info.init")))= { \ .nr = MACH_TYPE_##_type, \ .name = _name, #define MACHINE_END \ };
struct machine_desc也是定义在arch/arm/include/asm/mach/arch.h
struct machine_desc { /* * Note! The firstfour elements are used * by assembler codein head.S, head-common.S */ unsigned int nr; /* architecture number */ unsigned int phys_io; /* start of physical io */ unsigned int io_pg_offst; /* byte offset for io * page tabe entry */ const char *name; /* architecture name */ unsigned long boot_params; /* tagged list */ unsigned int video_start; /* start of video RAM */ unsigned int video_end; /* end of video RAM */ unsigned int reserve_lp0:1; /* never has lp0 */ unsigned int reserve_lp1:1; /* never has lp1 */ unsigned int reserve_lp2:1; /* never has lp2 */ unsigned int soft_reboot:1; /* soft reboot */ void (*fixup)(struct machine_desc *, struct tag *, char **, struct meminfo *); void (*map_io)(void); /* IO mapping function */ void (*init_irq)(void); struct sys_timer *timer; /* system tick timer */ void (*init_machine)(void); };
3. MACH HALIBUT的定义
把1中定义的MACH展开之后，得到：