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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 ...
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  1. #1
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    Major and minor numbers


    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.

  2. #2
    Just Joined! vijay_kernel's Avatar
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    As per my knowledge 1 Major number can have many minor numbers. So I think only minor number will change here.

  3. #3
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  4. #4
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    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.

  5. #5
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    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)

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