At 2014/6/14 22:36, Greg KH wrote: > On Sat, Jun 14, 2014 at 10:58:53AM +0800, Simon Guo wrote: >> Forward to USB mail alias for the USB question. >> >> -------- Original post -------- >> Subject: Question about USB hotplug >> Date: Sat, 14 Jun 2014 09:59:45 +0800 >> Sender: Simon Guo <wei.guo.simon@xxxxxxxxx> >> Receiver: kernelnewbies@xxxxxxxxxxxxxxxxx, wei.guo.simon@xxxxxxxxx >> >> Hi, dear list, >> >> I want to be clear about the USB hotplug procedure. >> >> I read "Linux Device Driver" and "Documentation/usb/hotplug.txt", and >> google much. Per my understanding, the USB hotplug works as following: >> 1) Insertion of physical U-disk will trigger a hardware interrupt. And >> interrupt handler (installed by USB bus driver?) will create kobj at /sys. >> 2) According to Linux device model, the creation of kobj will raise >> hotplug event (implemented in USB bus driver). >> 3) user space hotplug helper is invoked to handle hotplug event. Hotplug >> helper will read "modules.usbmaps" and decide to load which USB driver. >> If there are many drivers matching the device, they will all be loaded? >> 4) udev will create approparite dev under /dev according to rules defined. >> Please correct me if I am wrong in the above. >> >> I am using Ubuntu 11, and with my own build kernel version 3.15.0. > > Please ask on a Ubuntu mailing list, they are the only distro that > people have problems with this, so they must be doing something "odd" > compared to everyone else. > Thanks Greg. The feedback from Ubuntu list indicates udev(which was developed by you) is used to handle hotplug, and the procedure I listed was out-of-date. Whereas "Documentation/usb/hotplug.txt" doesn't mention udev at all. BR, Simon _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
