Node creation For real time devices

[Li Haifeng]

A good question.

When a driver is probed, corresponding device file will be created in
sysfs or devfs.

Maybe you can take a look at this link: http://lwn.net/Articles/330985/

Regards,
Haifeng Li

在 2012年4月20日 下午10:04，manty kuma <mantykuma at gmail.com> 写道：
> Hi Philipp,
>
> The flow you mentioned is something which I was not aware of. I would like
> to see it happening in code.
>
> My Queries are as follows:
>
> 1) " The kernel then creates an uevent and notifies the userspace part of
> udev (udevd) through a netlink socket. " -  What are the corresponding files
> that i need to check? If the question is too abstract, kindly explain me
> with respect to any sample Bus.
>
> 2)  "The uevent is received by udevd and now udev can check for rules to add
> the device node to /dev" - Again the same thing. I would like to see it
> inside the code. Please help me in looking at the real code.
>
> Thanks again Philipp for your valuable answer.
>
> Regards,
> -Manty
>
> On Fri, Apr 20, 2012 at 7:24 PM, Philipp Ittershagen
> <p.ittershagen at googlemail.com> wrote:
>>
>> Hi Manty!
>>
>> On Fri, Apr 20, 2012 at 3:29 PM, manty kuma <mantykuma at gmail.com> wrote:
>> > Hi,
>> >
>> > I want to know how a node is created when a hardware is connected to the
>> > system.
>> >
>> > Information that I know :
>> > When a hardware is connected to the system, the device name is compared
>> > with
>> > the driver name, if it matches, then probe is called.
>> >
>> > Info i wish to know:
>> > At which point is the node created and who is creating it(In other
>> > words, i
>> > want to know where is mknod happening)?
>> >
>> > This one thing is bugging my mind from so many months. Please tell me
>> > programatically where is this happening. I will be very thankful.
>>
>> Please correct me if I'm wrong, my understanding is this:
>>
>> The hardware is connected and the corresponding subsystem or bus will
>> be notified (i.e. by interrupt of the device). The kernel then creates
>> an uevent and notifies the userspace part of udev (udevd) through a
>> netlink socket. The uevent is received by udevd and now udev can check
>> for rules to add the device node to /dev. That's when the creation and
>> naming of the device node happens.
>>
>>
>> Greetings,
>>
>>  Philipp
>
>
>
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