From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,bc1361a952ec75ca X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2001-08-05 01:13:07 PST Path: archiver1.google.com!newsfeed.google.com!newsfeed.stanford.edu!news.tele.dk!151.189.0.75!newsfeed.germany.net!newsfeed2.easynews.net!easynews.net!news.cid.net!news.enyo.de!news1.enyo.de!not-for-mail From: Florian Weimer Newsgroups: comp.lang.ada Subject: Re: How Ada could have prevented the Red Code distributed denial of service attack. Date: Sun, 05 Aug 2001 10:30:37 +0200 Organization: Enyo's not your organization Message-ID: <871ymqaoya.fsf@deneb.enyo.de> References: <87r8uvuu48.fsf@deneb.enyo.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Xref: archiver1.google.com comp.lang.ada:11306 Date: 2001-08-05T10:30:37+02:00 List-Id: tmoran@acm.org writes: >> Actually, it was the 286. The 386 introduced another VM layer which >> supports paging, IIRC. > Wasn't the 286 selector stuff a whole lot simpler than the 386? I don't think so. You already had those four rings (courtesy of Multics, I guess), this mysterious ARPL instruction, call gates, etc. etc. In fact, the 386 is simpler than the 286 for implementing C-oriented operating systems because of the additional VM layer which permits an unsegmented address space for user-mode programs. > Is it the case that it was impossible, or at least nobody ever > managed, to make an OS that actually used the 386 stuff? I don't know. Perhaps you can implement the Ada rendezvous efficiently using call gates. Some of the stuff is of course used by each modern operating system, in order to switch to protected mode. But Linux, for example, does all the fancy stuff using the additional VM layer which was added by the 386.