Date: Sun, 18 Jan 1998 05:37:01 -0800 (PST) From: asami@cs.berkeley.edu (Satoshi Asami) To: ksmm@cybercom.net Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: what does MMX mean? Message-ID: <199801181337.FAA13330@baloon.mimi.com> In-Reply-To: <Pine.BSI.3.95.980116223422.7031A-100000@kalypso.cybercom.net> (message from The Classiest Man Alive on Fri, 16 Jan 1998 22:38:02 -0500 (EST))
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* : The MMX registers are aliases of regular FP registers. (They did not * : want to add any new registers or flags -- so the OS doesn't need to be * : aware of new MMX chips and the applications can still use them.) So * : it won't help if you want to do a lot of FP operations intermixed with * : MMX operations. * * Is this true for the Pentium II as well? I believe so. The Intel designer who gave a talk here awhile ago said they didn't want old operating systems to break because of new chips and new applications. What this means is that since OS's only save/restore the registers it knows about upon a context switch, you can't add a new register without having the OS support it explicitly. Satoshi
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