Re: [PATCH v10 0/7] Add Fieldbus subsystem + support HMS Profinet card

From: Enrico Weigelt, metux IT consult
Date: Tue Apr 16 2019 - 17:19:40 EST

On 16.04.19 20:56, Sven Van Asbroeck wrote:

>> By the way: any special reason for doing this via device instead of
>> socket (like we have w/ can) ?
> A fieldbus_dev device communicates with its controller through a section
> of shared memory (process memory). It just felt more logical to model
> this as a device which acts like a file. When you read/write the file,
> you read/write the process memory underneath.

Yeah, that sounds logical. By the way: could we also mmap() that device?

Okay that's just a purely academical idea here, but I'm curious whether
that would make a notable difference in performance.

Yet another question: does each fieldbus_dev instance talk to exactly
one plc process memory, or can there be many ?

Having separate device nodes per plc process memory seems a good idea
for finer access control (via chown+friends).


Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@xxxxxxxxx -- +49-151-27565287