cmdline -[command line,__fdt_pointer,initial_boot_params] boot_command_line 获取

[boot_command_line,cmdline,commandline,devicetree地址]

head.S->start_kernel(), head.S 中主要是获取dt的地址：

str_l    x21, __fdt_pointer, x5        // Save FDT pointer

>>start_kernel() -- main.c

        >>setup_arch() --setup.c

                >>setup_machine_fdt()

                        >>early_init_dt_scan()  --fdt.c

                                >>early_init_dt_verify()   --fdt.c ;check __fdt_pointer后，赋给initial_boot_params

                                >>early_init_dt_scan_nodes()  --fdt.c ;最终获取devicetree参数

                                     >>early_init_dt_scan_chosen --fdt.c; 获取command line 参数

setup_arch(&command_line);

command_line 是对 全局变量boot_command_line的一个引用

setup_machine_fdt()

__fdt_pointer 经过fixmap_remap_fdt(dt_phys) 映射后，往下传参

early_init_dt_scan_nodes

获取 command_line参数,给boot_command_line 赋值

获取memory参数

int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
                     int depth, void *data)
{
    int l;
    const char *p;

    pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);

    if (depth != 1 || !data ||
        (strcmp(uname, "chosen") != 0 && strcmp(uname, "[email protected]") != 0))
        return 0;

    early_init_dt_check_for_initrd(node);

    /* Retrieve command line */
    p = of_get_flat_dt_prop(node, "bootargs", &l);
    if (p != NULL && l > 0)
        strlcpy(data, p, min((int)l, COMMAND_LINE_SIZE));   //拷贝到 boot_command_line

    /*
     * CONFIG_CMDLINE is meant to be a default in case nothing else
     * managed to set the command line, unless CONFIG_CMDLINE_FORCE
     * is set in which case we override whatever was found earlier.
     */
#ifdef CONFIG_CMDLINE
#if defined(CONFIG_CMDLINE_EXTEND)
    strlcat(data, " ", COMMAND_LINE_SIZE);
    strlcat(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
#elif defined(CONFIG_CMDLINE_FORCE)
    strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
#else
    /* No arguments from boot loader, use kernel's  cmdl*/
    if (!((char *)data)[0])
        strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
#endif
#endif /* CONFIG_CMDLINE */

    pr_debug("Command line is: %s\n", (char*)data);

    /* break now */
    return 1;
}

void __init early_init_dt_scan_nodes(void)
{
    /* Retrieve various information from the /chosen node */
    of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);

    /* Initialize {size,address}-cells info */
    of_scan_flat_dt(early_init_dt_scan_root, NULL);

    /* Setup memory, calling early_init_dt_add_memory_arch */
    of_scan_flat_dt(early_init_dt_scan_memory, NULL);
}