linux kernel 从cmdline 提取值

// 从cmdline 提取 rootfsname= 的值到 val_buf                                         
char val_buf[64];
#define ROOTFS_CMDLINE "rootfsname="

static void __init gluebi_read_cmdline (void)
{
    rootfsmtd_ptr = strstr(saved_command_line, ROOTFS_CMDLINE);
    if (rootfsmtd_ptr) {
        sscanf(rootfsmtd_ptr, ROOTFS_CMDLINE"%s", val_buf);
        printk("Gluebi: Found kernel commandline option 'rootfsname=%s'
", val_buf);
    }   
}

// drivers/acpi/sysfs.c
static int param_get_trace_state(char *buffer, struct kernel_param *kp)
{
    if (!acpi_gbl_trace_method_name)
        return sprintf(buffer, "disable");
    else {
        if (acpi_gbl_trace_flags & 1)
            return sprintf(buffer, "1");
        else
            return sprintf(buffer, "enable");
    }
    return 0;
}
static int param_set_trace_state(const char *val, struct kernel_param *kp)
{
    int result = 0;

    if (!strncmp(val, "enable", sizeof("enable") - 1)) {
        result = acpi_debug_trace(trace_method_name, trace_debug_level,
                      trace_debug_layer, 0);
        if (result)
            result = -EBUSY;
        goto exit;
    }

    if (!strncmp(val, "disable", sizeof("disable") - 1)) {
        int name = 0;
        result = acpi_debug_trace((char *)&name, trace_debug_level,
                      trace_debug_layer, 0);
        if (result)
            result = -EBUSY;
        goto exit;
    }

    if (!strncmp(val, "1", 1)) {
        result = acpi_debug_trace(trace_method_name, trace_debug_level,
                      trace_debug_layer, 1);
        if (result)
            result = -EBUSY;
        goto exit;
    }

    result = -EINVAL;
exit:
    return result;
}
                                                                                    
// 设置 从cmdline 分析到 trace_state 参数 调用param_set_trace_state, 将值传给 buffer
module_param_call(trace_state, param_set_trace_state, NULL, NULL, 0);

// init/main.c

static int __init set_reset_devices(char *str)
{
    reset_devices = 1;
    return 1;
}

__setup("reset_devices", set_reset_devices);