udev/hotplug and automatic /dev node creation

udev/hotplug and automatic /dev node creation

[Horst Schirmeier]

Hi,

I'm looking for documentation regarding how to write a Linux kernel
module that creates its own /dev node via udev/hotplug.
register_chrdev() and a simple udev/rules.d/ entry don't seem to be
sufficient...

Any suggestions on where to start reading are welcome.

Kind regards,
 Horst

-- 
PGP-Key 0xD40E0E7A

Re: udev/hotplug and automatic /dev node creation

[Greg KH]

On Wed, Jan 18, 2006 at 03:47:10AM +0100, Horst Schirmeier wrote:
> Hi,
> 
> I'm looking for documentation regarding how to write a Linux kernel
> module that creates its own /dev node via udev/hotplug.
> register_chrdev() and a simple udev/rules.d/ entry don't seem to be
> sufficient...

Yes, register_chrdev() will do nothing for udev.

Take a look at the book, Linux Device Drivers, third edition (free
online).  In the chapter about the driver model, there is a section
about what udev needs.  The functions it says to use are no longer in
the kernel, but it should point you in the right direction (hint, use
class_device_create().)

If you have a pointer to your code, I can probably knock out a patch for
you very quickly.

thanks,

greg k-h

Re: udev/hotplug and automatic /dev node creation

[Horst Schirmeier]

On Tue, 17 Jan 2006, Greg KH wrote:
> On Wed, Jan 18, 2006 at 03:47:10AM +0100, Horst Schirmeier wrote:
> > Hi,
> > 
> > I'm looking for documentation regarding how to write a Linux kernel
> > module that creates its own /dev node via udev/hotplug.
> > register_chrdev() and a simple udev/rules.d/ entry don't seem to be
> > sufficient...
> 
> Yes, register_chrdev() will do nothing for udev.
> 
> Take a look at the book, Linux Device Drivers, third edition (free
> online).  In the chapter about the driver model, there is a section
> about what udev needs.  The functions it says to use are no longer in
> the kernel, but it should point you in the right direction (hint, use
> class_device_create().)

Thank you very much, I'll look into this book and class_device_create().

> If you have a pointer to your code, I can probably knock out a patch for
> you very quickly.

I have no doubt you'll be able to do that, but my primary intention is
to dig into that myself :) thanks again.

Kind regards,
 Horst

-- 
PGP-Key 0xD40E0E7A

Re: udev/hotplug and automatic /dev node creation

[Horst Schirmeier]

On Tue, 17 Jan 2006, Greg KH wrote:
> On Wed, Jan 18, 2006 at 03:47:10AM +0100, Horst Schirmeier wrote:
> > Hi,
> > 
> > I'm looking for documentation regarding how to write a Linux kernel
> > module that creates its own /dev node via udev/hotplug.
> > register_chrdev() and a simple udev/rules.d/ entry don't seem to be
> > sufficient...
> 
> Yes, register_chrdev() will do nothing for udev.
> 
> Take a look at the book, Linux Device Drivers, third edition (free
> online).  In the chapter about the driver model, there is a section
> about what udev needs.  The functions it says to use are no longer in
> the kernel, but it should point you in the right direction (hint, use
> class_device_create().)
> 
> If you have a pointer to your code, I can probably knock out a patch for
> you very quickly.

Now I'm using class_create() and class_device_create() (together with
class_device_destroy() and class_destroy()), which works fine on
2.6.15 and 2.6.16-rc1, and with some hackish LINUX_VERSION_CODE-checking
#define wrapper around class_device_create() also on 2.6.13 and
2.6.14...

But: Is there a common way to get this working on 2.6.12 or earlier?

Kind regards,
 Horst

-- 
PGP-Key 0xD40E0E7A

Re: udev/hotplug and automatic /dev node creation

[Greg KH]

On Wed, Jan 25, 2006 at 01:50:17PM +0100, Horst Schirmeier wrote:
> On Tue, 17 Jan 2006, Greg KH wrote:
> > On Wed, Jan 18, 2006 at 03:47:10AM +0100, Horst Schirmeier wrote:
> > > Hi,
> > > 
> > > I'm looking for documentation regarding how to write a Linux kernel
> > > module that creates its own /dev node via udev/hotplug.
> > > register_chrdev() and a simple udev/rules.d/ entry don't seem to be
> > > sufficient...
> > 
> > Yes, register_chrdev() will do nothing for udev.
> > 
> > Take a look at the book, Linux Device Drivers, third edition (free
> > online).  In the chapter about the driver model, there is a section
> > about what udev needs.  The functions it says to use are no longer in
> > the kernel, but it should point you in the right direction (hint, use
> > class_device_create().)
> > 
> > If you have a pointer to your code, I can probably knock out a patch for
> > you very quickly.
> 
> Now I'm using class_create() and class_device_create() (together with
> class_device_destroy() and class_destroy()), which works fine on
> 2.6.15 and 2.6.16-rc1, and with some hackish LINUX_VERSION_CODE-checking
> #define wrapper around class_device_create() also on 2.6.13 and
> 2.6.14...
> 
> But: Is there a common way to get this working on 2.6.12 or earlier?

Look at the class_simple* functions in that older kernel version.  They
should do much of the same thing of what you need.

Hope this helps,

greg k-h