Path: utzoo!mnetor!uunet!husc6!mailrus!ames!oliveb!amiga!neil
From: neil@amiga.UUCP (Neil Katin)
Newsgroups: comp.sys.amiga
Subject: Re: Why is there a mount but no unmount?
Message-ID: <2047@amiga.UUCP>
Date: 22 Apr 88 23:51:38 GMT
References: <4643@garfield.UUCP> <242@ssbell.UUCP> <6090@swan.ulowell.edu> <2825@tekigm2.TEK.COM>
Reply-To: neil@amiga.UUCP (Neil Katin)
Organization: Commodore-Amiga Inc., 16795 Lark Ave. Suite 106, Los Gatos CA 95030
Lines: 23
Keywords: mount unmount path

I'm going to assume you mean "unload" as in unload a device handler from
memory.  We already have unmount: a volume goes away when no one is
using it (e.g. floppies).

There are two reasons why we don't have an "unload" command in amiga-dos:
one political and one technical.

The political reason is that TRIPOS did not have it, and the person in
charge of the dos (who will remain nameless) did not think it was important
enough; after all, it was a single user machine and you could always
reboot.

The technical reason are very sticky: it revolves around the problem of
there being no access control to the dos's device list.  This means
that while you can add things to the list, you can never safely
remove them because someone might have your device node in hand while
you are removing it.  This is a small window of vulnerability, but
a nasty one when it happens.  We live with the problem for removing
aliases and volumes now, though.

The other problem is that people can get a handle on the device handlers
message port (via DeviceProc()).  This handle is valid "forever", so
you can never make a handler go away.  Sorry, but that's life.