Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: "Paul A. Clayton" Newsgroups: comp.arch Subject: Re: Privilege Levels Below User Date: Thu, 13 Jun 2024 19:09:41 -0400 Organization: A noiseless patient Spider Lines: 31 Message-ID: References: <5h%8O.4327$wDZ.776@fx48.iad> <1316e4baa439de908666e38c39cd8c79@www.novabbs.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 14 Jun 2024 01:09:43 +0200 (CEST) Injection-Info: dont-email.me; posting-host="9bc529aa01f938c22a707fb859b26e71"; logging-data="2633583"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18wtFMOnUjqglKFo8KrvncMylIyJBajeUw=" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.0 Cancel-Lock: sha1:CMAGMVvBwkShvOOeYT3QSDd2QgM= In-Reply-To: <1316e4baa439de908666e38c39cd8c79@www.novabbs.org> Bytes: 2684 On 6/8/24 1:37 PM, MitchAlsup1 wrote: > EricP wrote: > >> Scott Lurndal wrote: [snip] >> What they found that not only do they not need 4 levels, >> it was a pointless overhead to have to constantly switch between them. >> (There is a pretty high penalty to switching modes, copying in args, >> validating args, doing something usually simple, then switching back, >> when it is all the OS's code anyway.) > > VAX was before common era Hypervisors, do you think VAX could have > supported secure mode and hypervisor with their 4 levels ?? > > But for similar reasons ring 1 and 2 are not used in x86 machines, > either. {{NOw, if we could just go back to 1982 and not invent > IDTs, and call gates, .....}} I thought My 66000 had Port Holes that are vaguely similar to call gates, so rather than "not invent" perhaps invent with better semantics and a better interface? (Though 1982 might have been too early to implement such. Better perceiving when to wait for the technology or understanding to implement something better is presumably one of the skills acquired by long experience as well as the related what can be implemented to provide the most attractive/marketable features without excessively limiting future developments. Letting a competitor provide a temporarily better product — or delaying entry into a market expecting a feature — can sometimes be sensible if one expects to leapfrog with a better long-term alternative, but "worse is better" has some truth.)