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From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.programmer,comp.sys.amiga.hardware,adsp.sw,adsp.hw
Subject: Re: 68040 Compatibility Warning
Message-ID: <22299@cbmvax.commodore.com>
Date: 10 Jun 91 16:15:12 GMT
References: <22139@cbmvax.commodore.com> <22146@cbmvax.commodore.com> <22154@cbmvax.commodore.com> <107299@becker.UUCP>
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 25

In article <107299@becker.UUCP> bdb@becker.UUCP (Bruce D. Becker) writes:
>In article <22154@cbmvax.commodore.com> mks@cbmvax.commodore.com (Michael Sinz) writes:
>|The 68040 (and future processors) will continue in the trend to push
>|the I and D spaces further apart.  The main reason is for system performance.

>       The Amiga OS just happens to
>	give so little protection at the application level that applications
>	have been written that will need to understand the issues of cache
>	coherency and separate I and D caches. 8^)

Unless it's trying to get away with self-modifying code, an application does
not need to know about cache issues.  If it is doing that kind of thing, it
has the choice of "know about it" or "fail".  In a protected OS, your choice
should be limited to "fail", since the OS will maintain code segments as read
only.  So in either case, if you're doing the right thing, you have no problems
and need to take no special considerations. 

The programs that NEED to know about cache issues are programs that are doing
OS type things, such as device drivers.

>  ,u,	 Bruce Becker	Toronto, Ontario
-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
	"This is my mistake.  Let me make it good." -R.E.M.