Messages in this thread |  | | | Date | Wed, 15 Oct 2008 10:45:10 +0200 | | From | "Kay Sievers" <> | | Subject | Re: Creating dev nodes from driver or via uevent? |
On Wed, Oct 15, 2008 at 8:39 AM, Fabiano Sidler <lists@fipscode.ch> wrote:
> Probably a very basic question, but is it better to directly mknod from a
> module's init funtion or to use the uevent/udev mechanism?
You better do not touch any userspace managed filesystem from inside
the kernel. No driver is doing that.
> If the latter,
> are there good overviews, explanations and comprehensive code samples
> especially for using udev, as well as how to package the userspace program
> creating the nodes along with a driver?
You do not package anything along with the driver, unless you have
_very_ special requirements for userspace device setup. Then you could
ship a udev rules file.
There is nothing special to do, just run udev, and register a "struct
device" inside the kernel's driver core, and you will see a device
node in /dev/ with the name of your kernel device, and the major/minor
you assigned to the struct device before registration.
Almost every Linux distro, and every driver in the kernel works that
way. I suggest looking at the current kernel code and running a Linux
distro and loading/unloading an existing module, to see it working.
You can also run "/sbin/udevadm monitor --env --kernel" to see the
"raw" kernel events "struct device" registration causes, and which
lets userspace create the device nodes.
Kay
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