Path: ...!weretis.net!feeder9.news.weretis.net!i2pn.org!i2pn2.org!.POSTED!not-for-mail From: mitchalsup@aol.com (MitchAlsup1) Newsgroups: comp.arch Subject: Re: Privilege Levels Below User Date: Thu, 13 Jun 2024 23:48:14 +0000 Organization: Rocksolid Light Message-ID: <3f74838dec0fa5fd4df0ec1e2bb6f6bc@www.novabbs.org> 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-Info: i2pn2.org; logging-data="4115748"; mail-complaints-to="usenet@i2pn2.org"; posting-account="65wTazMNTleAJDh/pRqmKE7ADni/0wesT78+pyiDW8A"; User-Agent: Rocksolid Light X-Rslight-Site: $2y$10$Dab7cD4LlSZbZX6l/mXPA.1ipq4gS/Y4rzZwGB4dQPG54/ODI/iSW X-Spam-Checker-Version: SpamAssassin 4.0.0 X-Rslight-Posting-User: ac58ceb75ea22753186dae54d967fed894c3dce8 Bytes: 3038 Lines: 47 Paul A. Clayton wrote: > 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? I would place them congruent to Load-From and Store-TO PDP-11/70 instructions. I have since converted to a more Linux friendly MMU structure. Port Holes can be easily resurrected. > (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.) It seems that in terms of computer architectures, the world is not going to beat a path to your door even if you invent a better mousetrap.