On Sun, 16 Nov 2014, me storage wrote:
Hi All,
I am reading chapter 3 in LDD3 i checked same topics in LDD2 so i got some confusions.According to my understanding Major number is used by kernel to identify the driver i.e major number tells about driver . Minor number is used by the driver module to know about the device which is using this module i.e minor number related to device number can i any one please tell am i correct? if wrong please explain me a bit more
for the most part, that is entirely correct -- the major number identifies the driver (either block or char), and you can see the current list of registered drivers with: $ cat /proc/devices Character devices: 1 mem 4 /dev/vc/0 4 tty 4 ttyS 5 /dev/tty 5 /dev/console 5 /dev/ptmx 7 vcs 10 misc 13 input ... Character devices: 1 mem 4 /dev/vc/0 4 tty 4 ttyS 5 /dev/tty 5 /dev/console 5 /dev/ptmx 7 vcs 10 misc 13 input ... and while the minor number *usually* then identifies a particular instance of a device being controlled by that driver, it doesn't *have* to. in fact, the driver is free to interpret the minor number any way it wants but, as you suggest, it typically just refers to a specific instance of a device. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================