[TUHS] Emacs and undump

Johnny Billquist bqt at update.uu.se
Tue Feb 28 07:06:10 AEST 2017


On 2017-02-27 21:26, Lars Brinkhoff wrote:
> Johnny Billquist wrote:
>> But having the memory around for a program, even if it is not running,
>> is actually sometimes very useful. If ITS could handle that, while
>> treating them as separate processes, all associated to one terminal,
>> and let you select which one you were currently fooling around in,
>> while the others stayed around, that is something I don't think I've
>> seen elsewhere.
>
> And it's not just a list structure, but a tree.  You can e.g. start a
> new DDT, which itself can have inferior jobs (subprocesses).

Hmm. That sounds similar to TOPS-20 then maybe.

>> So, Emacs does it once, and then saves the state at the point where
>> you can start editing.  But it does not mean that the memory is
>> shareable. It's full of various data structures, and code, and that
>> will change as you go along editing things as well.
>
> Much is sharable.  There's a concept of purification (which also comes
> from ITS).  A purecopy() function is used in temacs to put read-only
> data in a special memory area.  That area will become sharable in the
> dumped Emacs.

There are definitely some shareable things, but you need to remember 
that even some pure, read-only data can be problematic in a shared 
segment, as not all people might even have that data loaded, even if the 
data itself is readonly.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol


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