From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.5-pre1 (2020-06-20) on ip-172-31-74-118.ec2.internal X-Spam-Level: X-Spam-Status: No, score=-1.9 required=3.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.5-pre1 Path: eternal-september.org!reader02.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED.2uCIJahv+a4XEBqttj5Vkw.user.gioia.aioe.org!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: is there a version of unix written in Ada Date: Wed, 30 Sep 2020 23:03:28 +0200 Organization: Aioe.org NNTP Server Message-ID: References: <00cd3aaa-d518-43a2-b321-58d6fae70aebo@googlegroups.com> <57eb7a65-51ea-4624-b9dc-9c4dda0fee59n@googlegroups.com> <5f70fd3b$0$13541$426a74cc@news.free.fr> <87wo0d3iac.fsf@nightsong.com> <87sgb02l7b.fsf@nightsong.com> <875z7vyy1u.fsf@nightsong.com> <87wo0bkns3.fsf@nightsong.com> NNTP-Posting-Host: 2uCIJahv+a4XEBqttj5Vkw.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 X-Notice: Filtered by postfilter v. 0.9.2 Content-Language: en-US Xref: reader02.eternal-september.org comp.lang.ada:60346 List-Id: On 30/09/2020 22:33, Paul Rubin wrote: > "Dmitry A. Kazakov" writes: >> I want an OS protecting from compilers I do not trust without >> performance loss. > > That is not possible. Traditional OS's use memory protection hardware > for that, but that hardware introduces performance loss. I do not see why loss must be any bigger that other means of synchronization. > Singularity > aimed to avoid the loss by relying on trusted compilers. 1. You still have to share memory and use global resources for interlocking etc. 2. I would argue that hardware-assisted virtualization and insulation of processes produces more lean and effective code than cooperative model. Lack of virtualization leads to abstraction inversion and all sorts of low-level programming tricks that make code very ugly, fragile and quite inefficient. E.g. in Ada absence of co-routines leads to using state machines which turns everything upside down and inefficient too. > It's not > anything like MSDOS, since MSDOS never tried to coordinate multiple > processors and intercommunicating processes. Both deploy a cooperative model of sharing resources. P.S. Surely MS-DOS coordinated auxiliary processors, there exited lots of expansion cards with processors on them in MS-DOS times. P.P.S. In MS-DOS processes were coordinated using glorious INT 21h. (:-)) -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de