Major and minor numbers

[rajkumarmadhani]

Hi,

I am having doubt regarding Major no& minor no in drivers.

suppose iam having 3 same serial drivers for one device.

1) is major no is same for all 3 drivers ?
2) where the minor no's will do what is contribution of minor no's.
3)and how the user would know how to access that particular driver

could any body please explain me.

[vijay_kernel]

As per my knowledge 1 Major number can have many minor numbers. So I think only minor number will change here.

[Lakshmipathi]

Check for doc Here

[Chandra Sekhar R]

Major number identifies the driver.
Minor number identified the instance of the device.

YOu can have multiple devices of same type.
For one device type you can have only one driver.

[icortazar3]

Major number is used as index into a table of functions, Then each different driver (set of C functions that constitute an entry of the table) has to have a different major number.

Minor number is a parameter that is passed to these functions, usually to distinguish between different physical devices handled by the same driver (set of functions)