Re: Getting Emacs to talk to Schemix

[Dr William Bland]

On Wed, Apr 23, 2003 at 09:51:29PM -0400, Richard Stallman wrote:
> 
>           I am writing Schemix (http://savannah.nongnu.org/projects/schemix
>     and http://www.abstractnonsense.com/schemix).  Briefly, Schemix is a
>     Scheme system embedded in the Linux kernel.  It presents a REPL on a
>     device, /dev/schemix.
> 
> In what way is this more useful than having a Scheme interpreter
> outside the kernel?  There are many advantages of modularity and
> security from keeping it outside the kernel.

I completely agree that a "normal" Scheme system (one intended for running
programs for users) does not belong in the kernel.  Schemix should not be
used for running such programs.

The intended uses of Schemix are those where you require quick,
interactive access to the kernel's internals.  For example, you might want
a new kernel interface that looks like the ones you find in /proc.
You could write this interface in C.  Suppose though, that you want to
invest very little time in writing the interface, compiling it and getting
it up and running.  Suppose further, that you haven't quite decided on
the format in which you want the interface to present its information to
the outside world, so you'd like to try several different versions before
you stick with one.  Suppose you don't want to reboot to get the interface
running.  Suppose you only want the interface to exist for a few minutes
and then to go away when you are finished using it.

This is one example of the kind of thing I'm suggesting people use Schemix
for, and you couldn't do it (as far as I know) with a Scheme interpreter
outside the kernel.

As far as security goes, /dev/schemix is created only read-writable by
root.  If the owner of the box has finished using Schemix then
"echo '(exit)' > /dev/schemix" causes the device to cease to exist (and
frees any memory it was using).

Best wishes,
                Bill.
-- 
Dr. William Bland.                          Computer Programmer, UK.
www.abstractnonsense.com