Path: utzoo!attcan!uunet!pdn!palan!ckctpa!crash
From: crash@ckctpa.UUCP (Frank J. Edwards)
Newsgroups: comp.sys.amiga
Subject: Re: Re: UNIX sys V4.0
Message-ID: <901025.222743@ckctpa.UUCP>
Date: 25 Oct 90 01:57:43 GMT
References: <6956@uwm.edu> <9010022@hpfcso.HP.COM>
Organization: Edwards & Edwards Consulting
Lines: 56

In article  <9010022@hpfcso.HP.COM>, aoe@hpfcso.HP.COM (Alexander Elkins) writes:
>ag@cbmvax.commodore.com (Keith Gabryelski) writes:
>>The port is out.  Ask questions about it and you will get answers.
>
>Alright - 1) Does it support shared code/libraries?  By shared code I mean
>two processes using the same code bytes in real memory.  By shared libraries
>I mean two different executables using the same library code bytes in real
>memory implying some kind of linking occurring, and if so how is it
>implemented?

If I understand correctly (and I think I do :-) since the Amiga Unix is
SysV.4 it will have shared libraries and read/only executable code sharing.

>2) Is the executable program code copied to virtual memory when it is run?

Considering that the processor can only execute code from *REAL MEMORY*
the answer is yes.  I think the question, however, should have been,
"can the executable code be run directly from the file on disk, or
does it take up paging space?"  In a lot of Unix environments nowadays
it is not necessary to load the program into virtual storage to execute
it, i.e. paging of the read/only portion of the file is performing
directly to the file on the disk (since it's only read, never written).

>3) Is virtual memory kept in a separate fixed size partition on the disk?

Again, on most Unix systems, "yes".  Some OS's (notably SunOS) allow
paging to be performed to a file instead of raw storage.  Personally,
I couldn't understand why you'd want this since you'd then have the
overhead of the filesystem getting in the way of I/O.  I don't know
enough about the Sun's /dev/swap file-or-device to make further
comments.

>Alexander Elkins

Good questions, A.E.

Now I have few:

1)  what is the minimum hard drive partition configuration?  Ie, how
small can my paging space be, and how many partitions are there minimum
(such as /, /usr, /tmp, et al).  I understand all of the variables
concerned -- number of concurrently running processes (for page
space) and other variables.  What is the *minimum*?

2)  BRU seems to have been written for use on both sides of the coin.
Is there other software slated that will be similarly available?

3)  What I've read in AT&T documentation seems to indicate at least
a minimal dynamically-configurable kernel.  Is this true?  Would that
include the ability to add/remove device drivers on-the-fly?
-----
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Edwards and Edwards Consulting	|   //_||   simply WASN'T any other choice!"
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