start_kernel 之 2
linux-2.6.14/arch/arm/kernel/setup.c
void __init setup_arch(char **cmdline_p)
{
struct tag *tags = (struct tag *)&init_tags;
struct machine_desc *mdesc;
char *from = default_command_line;
setup_processor();
mdesc = setup_machine(machine_arch_type);
/*
MACHINE_START(SMDK2410, "SMDK2410")
.phys_ram = S3C2410_SDRAM_PA, //0x30000000
.phys_io = S3C2410_PA_UART,
.io_pg_offst = (((u32)S3C24XX_VA_UART) >> 18) & 0xfffc,
.boot_params = S3C2410_SDRAM_PA + 0x100, //0x30000100
.map_io = smdk2410_map_io,
.init_irq = smdk2410_init_irq,
.timer = &s3c24xx_timer,
.init_machine = smdk2410_init_lcd,
MACHINE_END
*/
machine_name = mdesc->name; //SMDK2410
if (mdesc->soft_reboot)
reboot_setup("s");
if (mdesc->boot_params)
tags = phys_to_virt(mdesc->boot_params);
/*
#define PHYS_OFFSET (0x30000000UL)
#define PAGE_OFFSET (0xC0000000UL)
#define __phys_to_virt(x) ((x) - PHYS_OFFSET + PAGE_OFFSET)
#define __va(x) ((void *)__phys_to_virt((unsigned long)(x)))
static inline void *phys_to_virt(unsigned long x)
{
return (void *)(__phys_to_virt((unsigned long)(x)));
}
将引导参数存放位置从物理地址0x30000100转换到虚拟地址0xC0000100
*/
/*
* If we have the old style parameters, convert them to
* a tag list.
*/
if (tags->hdr.tag != ATAG_CORE)
convert_to_tag_list(tags);
if (tags->hdr.tag != ATAG_CORE)
tags = (struct tag *)&init_tags;
if (mdesc->fixup) //此成员函数很少在处理器中有定义，所以为空
mdesc->fixup(mdesc, tags, &from, &meminfo);
if (tags->hdr.tag == ATAG_CORE) {
if (meminfo.nr_banks != 0)
squash_mem_tags(tags);
parse_tags(tags);
}
init_mm.start_code = (unsigned long) &_text;
init_mm.end_code = (unsigned long) &_etext;
init_mm.end_data = (unsigned long) &_edata;
init_mm.brk = (unsigned long) &_end;
memcpy(saved_command_line, from, COMMAND_LINE_SIZE);
saved_command_line[COMMAND_LINE_SIZE-1] = '/0';
parse_cmdline(cmdline_p, from);
/*
mdesc->fixup = 0
tags->hdr.tag = 1413545985
_text = c0029000, _etext = c031de18, _edata = c03828f0, _end = c03abc70
*/
paging_init(&meminfo, mdesc);
request_standard_resources(&meminfo, mdesc);
cpu_init();
/*
* Set up various architecture-specific pointers
*/
init_arch_irq = mdesc->init_irq;
system_timer = mdesc->timer;
init_machine = mdesc->init_machine;
#ifdef CONFIG_VT
#if defined(CONFIG_VGA_CONSOLE)
conswitchp = &vga_con;
#elif defined(CONFIG_DUMMY_CONSOLE)
conswitchp = &dummy_con;
#endif
#endif
}
static void __init setup_processor(void)
{
struct proc_info_list *list;
/*
* locate processor in the list of supported processor
* types. The linker builds this table for us from the
* entries in arch/arm/mm/proc-*.S
*/
list = lookup_processor_type();
/*
根据汇编代码中获取的ARM处理器的主ID寄存器的值processor_id，从.proc.info
中找到该处理器对应的处理器信息结构struct proc_info_list型变量
*/
if (!list) {
printk("CPU configuration botched (ID %08x), unable "
"to continue./n", processor_id);
while (1);
}
cpu_name = list->cpu_name; //处理器名字
#ifdef MULTI_CPU
processor = *list->proc; //处理器处理函数组结构指针
#endif
#ifdef MULTI_TLB
cpu_tlb = *list->tlb; //TLB操作函数组结构指针
#endif
#ifdef MULTI_USER
cpu_user = *list->user; //处理器用户空间操作函数组
#endif
#ifdef MULTI_CACHE
cpu_cache = *list->cache; //cache操作函数组
#endif
printk("CPU: %s [%08x] revision %d (ARMv%s)/n",
cpu_name, processor_id, (int)processor_id & 15,
proc_arch[cpu_architecture()]);
//打印出上图中第四行的信息。
sprintf(system_utsname.machine, "%s%c", list->arch_name, ENDIANNESS);
//保存处理器架构名字字符串加”b”（big endian）或”l”（little endian）
sprintf(elf_platform, "%s%c", list->elf_name, ENDIANNESS);
//保存体系架构名字字符串加”b”（big endian）或”l”（little endian）
elf_hwcap = list->elf_hwcap;
//保存处理器硬件能力标志字
cpu_proc_init();
//处理器初始化函数指针，ARM体系下基本什么也不做
}
#define MACH_TYPE_SMDK2410 193
#ifdef CONFIG_ARCH_SMDK2410
# ifdef machine_arch_type
# undef machine_arch_type
# define machine_arch_type __machine_arch_type
# else
# define machine_arch_type MACH_TYPE_SMDK2410
# endif
# define machine_is_smdk2410() (machine_arch_type == MACH_TYPE_SMDK2410)
#else
# define machine_is_smdk2410() (0)
#endif
mdesc = setup_machine(machine_arch_type) // machine_arch_type = 193
static struct machine_desc * __init setup_machine(unsigned int nr)
{
struct machine_desc *list;
list = lookup_machine_type(nr);
/*
根据machine_arch_type(193)从当前系统的硬件平台编号从.arch.info中找到其对应 的平台描述结构machine_desc型变量。
*/
if (!list) {
printk("Machine configuration botched (nr %d), unable "
"to continue./n", nr);
while (1);
}
printk("Machine: %s/n", list->name);
//打印出上图中第五行的信息。
return list;
}