function of major/minor device number

[hz hanks]

Hi,  rday

Thank you for your help. Yes! You did point out my question. I will do
read drivers/char/misc.c for a better understanding.

Best,

2012/2/12 Robert P. J. Day <rpjday at crashcourse.ca>:
> On Sun, 12 Feb 2012, Alexandru Juncu wrote:
>
>> 2012/2/12 hz hanks <hankshz at gmail.com>:
>> > Hi, all
>> >
>> > I have a question about major/minor device number. I know that one can
>> > use int register_chrdev_region(dev_t from, unsigned count, const char
>> > *name); to register a driver with a unique pair of major/minor device
>> > number. But what's the difference between two drivers: in one case
>> > they have same major device number but different minor device number;
>> > on another case they have different major device number but same minor
>> > device number. When I searched the Internet, it said that major device
>> > number is to identify the driver while the minor device number is to
>> > identify specific hardware. But I'm still confused because it seems
>> > legal to share the major device number with different drivers.
>
>  you're talking about the "misc" character device driver here, which
> allows you to register very simple and independent character drivers
> that need only a single minor number all at major number 10.
>
>  look in /dev for how many char device files have major number 10.
> that's the perfect example of what you're talking about.  see the
> source in drivers/char/misc.c.
>
> rday
>
> --
>
> ========================================================================
> Robert P. J. Day                                 Ottawa, Ontario, CANADA
>                        http://crashcourse.ca
>
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