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Subject: Re: [PATCH v10 0/7] Add Fieldbus subsystem + support HMS Profinet
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To:     Sven Van Asbroeck <thesven73@gmail.com>
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From:   "Enrico Weigelt, metux IT consult" <lkml@metux.net>
Organization: metux IT consult
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Date:   Tue, 16 Apr 2019 23:18:10 +0200
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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).


--mtx

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