Re: Environment variables inside the kernel?

[Helge Hafting <helgehaf@aitel.hist.no>]

On Thu, Aug 18, 2005 at 08:48:04PM +0200, Guillermo López Alejos wrote:
> Whoa!, I did not expect so many replies. Thank you for your answers.
> 
> The thing is that the Computer Architecture area of the University I
> am studying at is developing a parallel filesystem. Currently it works
> as a stand-alone program (this is why it uses resources like
> environment variables), and I have been told to integrate it in the
> Linux kernel.
> 
> I have to justify changes on this filesystem code (like avoiding the
> use of environment variables) to my tutor. In this case I needed to
> find why it is not possible to use environment variables in kernel
> space.
> 
> I was looking for a reference documentation which give a definition of
> environment variables that exclude their use inside the kernel, or,
> simply, I expected to find a design decision to justify this. But I
> think I have enough information with your answers, I will be able to
> elaborate a satisfactory conclusion.
> 
> Excuse me if the topic was so obvious (it was not to me) and thank you again,

It is obvious to someone who knows what the kernel is. A kernel and
a process is very different things.  A comparison to something
different:

A book always have a "page 1".  It is usually only the title, so it
is a nice place for writing some notes as well. 
(similiar to how a process have an environment.)

A library is a big collection of books, (similiar to how the kernel
manages a collection of processes.)  Still, it does not make sense
at all to talk about "page 1 of the library!"  Even if it _is_ useful
to write some library-specific notes somewhere.

The kernel does not have an environment of its own.  It manages all
the processes, and jave equal access all of the environmnts 
(albeit in a hackish way only) for process envirnments are _not_
part of the kernel/process communication interface.  

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Helge Hafting