From owner-freebsd-hackers Sat May 2 06:50:03 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id GAA23639 for freebsd-hackers-outgoing; Sat, 2 May 1998 06:50:03 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from news.uni-kl.de (mmdf@news.uni-kl.de [131.246.137.51]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id GAA23572 for ; Sat, 2 May 1998 06:49:50 -0700 (PDT) (envelope-from mheller@student.uni-kl.de) Received: from alma.student.uni-kl.de by news.news.uni-kl.de id aa02135; 2 May 98 15:48 MET DST Received: from mater.student.uni-kl.de(really [131.246.90.23]) by alma.student.uni-kl.de via smtpd with smtp id for ; Sat, 2 May 1998 15:48:40 +0200 (CETDST) (Smail-3.2.0.95 1997-May-7 #5 built 1997-May-16) Received: from localhost by mater.student.uni-kl.de with smtp (Smail3.1.28.1 #1) id m0yVcef-0001gwC; Sat, 2 May 98 15:48 CETDST Date: Sat, 2 May 1998 15:48:41 +0200 (CETDST) From: Martin Heller To: dk+@ua.net cc: Peter Jeremy , freebsd-hackers@FreeBSD.ORG Subject: Re: VM architecture (was Re: Protected mode instructions which reduce In-Reply-To: <199805011730.KAA28217@dog.farm.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Fri, 1 May 1998, Dmitry Kohmanyuk wrote: > In article <199804262144.HAA29582@gsms01.alcatel.com.au> you wrote: > [...] > > On Fri, 24 Apr 1998 06:22:59 +0000 (GMT), Terry Lambert wrote: > > >The IBM VM architecture is logically complete -- that is, nearly all > > >of the instruction emulation implementation is in hardware, > > The VM kernel needs to provide a `virtual supervisor' mode. This can > > be quite expensive in software, so IBM provided microcode assist units > > which effectively made `virtual supervisor' mode part of the hardware > > machine mode. Pity that modern microprocessors don't have writable > > microcode. > > they do; modern Pentium series (starting with PPro if my memory serves > me right) contain user-modifyable area. Yep, the first processor from Intel to be able to do this was PPro. DEC Alpha processors have a more sophisticated approach from the beginning. This facility, known as PAL-code, is used to modify the processor for the operating system. > The Pentium F00F bug release from Intel specifically said that this bug > has to be dealt with in software because Pentiums are not updateable. I'm not shure if PPro and PII are updateable in such a way to fix something like this ... The only architecture known to me who can do this is the Alpha architecture from DEC. MARTIN To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message