Path: utzoo!attcan!uunet!cbmvax!valentin
From: valentin@cbmvax.commodore.com (Valentin Pepelea)
Newsgroups: comp.sys.m68k
Subject: Re: mc68040 I/D coherency
Message-ID: <12139@cbmvax.commodore.com>
Date: 2 Jun 90 01:48:03 GMT
References: <41463@brunix.UUCP> <12055@cbmvax.commodore.com> <12131@cbmvax.commodore.com>
Reply-To: valentin@cbmvax (Valentin Pepelea)
Organization: Commodore, West Chester, PA
Lines: 26

In article <12131@cbmvax.commodore.com> bryce@cbmvax (Bryce Nesbitt) writes:
>In article <> valentin@cbmvax (Valentin Pepelea) writes:
>>
>> 'They' chose not to support this practice at all. Writing self modifying
>> code (Ahem - self distructing code) is not just difficult, it's darn well
>> impossible on most systems.
>
> Darn well common.  Consider loading code from disk.  Or worse
> yet, a relocating loader.  The case is identical.

Loading code from disk, and even a relocating loader may run in supervisor mode,
where it has access to the internal registers which cause the cache to
clear or flush out.

On most Unix implementations, user code may never access supervisor-only
registers. And user code may not even write instruction space, particularly
not through a data manipulation instruction.

You still have a long way to go until you can refute my theories, Bryce.

Valentin
-- 
The Goddess of democracy? "The tyrants     Name:    Valentin Pepelea
may distroy a statue,  but they cannot     Phone:   (215) 431-9327
kill a god."                               UseNet:  cbmvax!valentin@uunet.uu.net
             - Ancient Chinese Proverb     Claimer: I not Commodore spokesman be