哇酷®开发者社区(WhyCan® Forum)

用的是V3s 4.13的版本，已经在menuconfig中设置了Kernel debugging，Kernel low-level debugging functions
在usb_disconnect这个函数中加了几句话，如下

void usb_disconnect(struct usb_device **pdev)
{
struct usb_port *port_dev = NULL;
struct usb_device udev = pdev;
struct usb_hub *hub = NULL;
int port1 = 1;
printk(KERN_NOTICE, "usb_disconnect begin\n");

/* mark the device as inactive, so any further urb submissions for

• this device (and any of its children) will fail immediately.

• this quiesces everything except pending urbs.
  */
  usb_set_device_state(udev, USB_STATE_NOTATTACHED);
  dev_info(&udev->dev, "AAUSB disconnect, device number %d\n",
  udev->devnum);
  _dev_info(&udev->dev, "BBBBUSB disconnect, device number %d\n",
  udev->devnum);
  printk(KERN_INFO, "---KERN_INFO usb_disconnect begin\n");
  printk(KERN_ALERT, "--- KERN_ALERTalert usb_disconnect begin\n");
  printk(KERN_WARNING, "---KERN_WARNING usb_disconnect begin\n");
  printk(KERN_NOTICE, "---KERN_WARNING usb_disconnect begin\n");
  printk(KERN_DEBUG, "---KERN_DEBUG usb_disconnect begin\n");
  .....
  }

输出结果为：
[ 35.141543] usb 2-1: AAUSB disconnect, device number 3
[ 35.146689] usb 2-1: BBBBUSB disconnect, device number 3

就是说dev_info，_dev_info两个函数可以输出，而printk函数没有输出，这是怎么回事啊？