[Xenomai-help] RTDM driver path question

[Xenomai-help] RTDM driver path question

[Sean McGranaghan]

Hello all,

I am in the process of writing a simple device driver for Xenomai 2.0 
using RTDM. I have a skeleton driver module loading and registering with 
RTDM. (I can see the entries in the /proc filesystem when the module 
loads.) I now want to write a driver validation application to exercise 
the interface, but don't know how Linux device nodes map to Xenomai 
devices. Do I have to manually create device nodes or are they built 
with udev? (I am more familiar with traditional Unix style /dev entries, 
udev is new to me.) Do Xenomai devices use the Linux filesystem layer at 
all? Does Xenomain keep a separate namespace/registry of named devices?

If I missed this in the documentation please feel free to redirect me as 
needed. Any help is appreciated.

Thanks,
Sean McGranaghan

Re: [Xenomai-help] RTDM driver path question

[Jan Kiszka]

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Sean McGranaghan wrote:
> Hello all,
> 
> I am in the process of writing a simple device driver for Xenomai 2.0
> using RTDM. I have a skeleton driver module loading and registering with
> RTDM. (I can see the entries in the /proc filesystem when the module
> loads.) I now want to write a driver validation application to exercise
> the interface, but don't know how Linux device nodes map to Xenomai
> devices. Do I have to manually create device nodes or are they built
> with udev? (I am more familiar with traditional Unix style /dev entries,
> udev is new to me.) Do Xenomai devices use the Linux filesystem layer at
> all? Does Xenomain keep a separate namespace/registry of named devices?

The RTDM namespace is totally separated from the Linux file system.
Thus, there is no dev node or "/dev/" name prefix - as long as you don't
prefer to register your device under "/dev/mydevice".

To differentiate between both namespaces, you address RTDM devices via
rt_dev_open/rt_dev_socket under most skins except for the POSIX skin.
The latter will tell them apart by first asking RTDM for a device to be
opened and then, if this fails, standard Linux.

> 
> If I missed this in the documentation please feel free to redirect me as
> needed. Any help is appreciated.

Hmm, maybe we rather missed to clearly state this aspect in the docs,
will have to check this.

Anyway, there is also an overview paper available now from the Real-Time
Linux Workshop 2005, Lille (www.realtimelinuxfoundation.org, but papers
are not yet online, I can send it to you privately).

Jan


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