linux根文件系统挂载

由bootload进入linux后由head.s进入了start_kernel了.
asmlinkage void __init start_kernel(void)
{
       char * command_line;
       extern struct kernel_param __start___param[], __stop___param[];
       ………………..
       setup_arch(&command_line);
       ………….
       ………..
       vfs_caches_init(num_physpages); ………….     
 
…………...
       rest_init();
}
 
重要函数解释
 
1.Setup_arch是解释bootloader传过来的参数，并附相关参数。
 
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_name = mdesc->name;
 
       if (mdesc->soft_reboot)
              reboot_setup("s");
 
       if (mdesc->boot_params)
              tags = phys_to_virt(mdesc->boot_params);
 
       /*
        * If we have the old style parameters, convert them to
        * a tag list.
        */
 &nb