[TUHS] Device special files

[clemc@ccc.com (Clem Cole)]

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On Wed, Feb 7, 2018 at 2:07 PM, Ian Zimmerman <itz at very.loosely.org> wrote:

>
>
> The real problem with static /dev is on the development side IMO -
> managing the namespace of device names and major/minor numbers.

​And that is the issue I think that Ron is reacting too.

One of the lines I have had about UNIX development is the number if
namespaces its has.  If you try to develop something like Single System
Image Clusters (check out OpenSSI.org) you'll hit all of the namespaces.

Let me see how many I can remember quickly..

   1. file system
   2. per device inumbers for storage
   3. device major numbers
   4. per device minor numbers
   5. pid
   6. gid
   7. sockets
   8. port numbers within sockets per protocol
   9. system V semaphores
   10. system V shared memory​


I'll stop here, you get the idea...

Ron is right managing the major/minor number externally which have internal
meaning to the kernel can be quite an issue.   Although, in fairness, it
has worked amazing well for over 40 years.  It was a simple solution and
did not take take up a lot of space in the kernel to implement.  I'm not
sure for the PDP-11, I would have wanted much more.   One might suggest it
was pretty damned elegant for the time.

Clem
ᐧ
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