Date: Sat, 2 May 1998 15:48:41 +0200 (CETDST) From: Martin Heller <mheller@student.uni-kl.de> To: dk+@ua.net Cc: Peter Jeremy <peter.jeremy@alcatel.com.au>, freebsd-hackers@FreeBSD.ORG Subject: Re: VM architecture (was Re: Protected mode instructions which reduce Message-ID: <Pine.A41.3.95.980502153433.105144A-100000@mater.student.uni-kl.de> In-Reply-To: <199805011730.KAA28217@dog.farm.org>
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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 <tlambert@primenet.com> 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
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