From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 16885 invoked from network); 8 Sep 2022 16:51:17 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 8 Sep 2022 16:51:17 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id 62FAE417A1; Fri, 9 Sep 2022 02:50:56 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tuhs.org; s=dkim; t=1662655856; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-owner:list-unsubscribe:list-subscribe:list-post; bh=zPVjaUmfK1c0Dulbjnw4PyUwB1B6gjFTuWoGSMfBfcY=; b=bfkmViIZ7wTWgC+krErv+3gMr+ED+ohFbbxsz+Vfs512byiFq5WixuBBNPwj5wqFEAD+qI rupMfvA5h2AtkGypbSiZzi/vr+1K7bTWsxP1KB0Dl3iBVn0vY755MyZ+p/RhYNG10CaYHp ZbjfefDDNKG/9Azv13pUdpg9cru0pb0= Received: from mail-4325.protonmail.ch (mail-4325.protonmail.ch [185.70.43.25]) by minnie.tuhs.org (Postfix) with ESMTPS id 72CDD4094F for ; Fri, 9 Sep 2022 02:50:51 +1000 (AEST) Date: Thu, 08 Sep 2022 16:50:43 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1662655849; x=1662915049; bh=zPVjaUmfK1c0Dulbjnw4PyUwB1B6gjFTuWoGSMfBfcY=; h=Date:To:From:Cc:Reply-To:Subject:Message-ID:In-Reply-To: References:Feedback-ID:From:To:Cc:Date:Subject:Reply-To: Feedback-ID:Message-ID; b=zNh0jHV2X7tMnU11fw6Nh3uW94gEeO9MV9b+u3YyPEzn4ysh4sFAy7O29YmU23MeZ 9dCqbF9yvwdOfan4no+REWLJ/1tvvJfSHPds7m6Z4FQaNoChUFowUAmt3CnLHfTudY UgWc0Oo3FLWi2oKPnCr2G033DmV1ERVKnez9jmUtXgHrXEK0GPr8EIi3dwRVjN0fTo wrzObstlKe9kXOxDZ+Dqn5tw8xatar6zjSE3wew99qf9jhJ/4nseaDXvUtXcLwI6av cHQHN7Pj+Gcrg5lIiVOnAiLTK52iHe3K0hZJbX/8vYxcvNH9lbq2JWsupA+NRuT3+T FdynEAw9lM2xg== To: Warner Losh Message-ID: In-Reply-To: References: <20220907145631.GN31856@mcvoy.com> <8DDF5A51-AABF-41AF-993C-4D087903BDC9@canb.auug.org.au> Feedback-ID: 35591162:user:proton MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Message-ID-Hash: RUOIIGGB5CMHI3LPRLPTBE3FRO6QULXU X-Message-ID-Hash: RUOIIGGB5CMHI3LPRLPTBE3FRO6QULXU X-MailFrom: segaloco@protonmail.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-tuhs.tuhs.org-0; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Steve Jenkin , TUHS X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: Has this been discussed on-list? How Unix changed Software. List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: From: segaloco via TUHS Reply-To: segaloco > In addition, when Dennis would talk about Coherent and his evaluation of = the source code, he said he used the known to him, but not widely known bug= s in Unix to try to catch copying. If there was copying, those would be cop= ied. If it was freshly implemented, there's a high likelihood that they wou= ldn't. His conclusion was that someone had access to a lot of knowledge abo= ut the Unix system given the fidelity of the implementation, but the lack o= f bugs and novel ways of doing it suggested independent implementation. Both Coherent and 4.4BSD have stuck out to me as examples of not-quite-so-c= lean-room implementations that did well enough (more than enough for BSD) a= nd didn't die a fiery death in litigation (as much as USL tried...). What = I find interesting is that in this day and age, it seems there is almost a = requirement for true "clean-room" implementation if something is going to b= e replicated, which I understand to mean the team developing the new implem= entation can't be the same team that performed a detailed analysis of the p= roduct being reimplemented, but the latter team can produce a white paper/w= riteup/memorandum describing the results of their analysis and the developm= ent team can then use that so long as it doesn't contain any implementation= details. I've always wondered how cleanly that sort of thing can actually be proven = and enforced, and I've always thought back to the Coherent situation as an = almost model example. Where proving copying outright can be difficult, kno= wing one's own product well enough to know the bugs that are incredibly obs= cure but also reliably consistent is a great way to peg a faithful recreati= on vs. a flat out copy job. That said, my assumption with complete UNIX re= -implementations is that folks at least had access to the manuals, perhaps = had used UNIX before in some capacity. I would assume the current definiti= on of a clean-room implementation only requires that the developers/impleme= ntors don't have access to the code of the parent product (source or revers= e engineered), but could read manuals, study behavior in-situ, and use that= level of "reverse engineering" to extract the design from the implementati= on, so not knowing the gritty details, Coherent could be a true clean-room. BSD is a different beast, as they were literally replacing the AT&T source = code before their eyes, so there isn't much argument that can be made for 4= .4BSD being a "clean-room" implementation of UNIX. Simply for compatibilit= y and upgrade-ability of existing systems, they had to be incredibly accura= te to the original design. Given that, that's one of the more surprising t= hings to me about 4.4BSD prevailing in the lawsuit, because while Berkeley = could easily prove that they had replaced most of AT&T's code, there's stil= l the fact that their team did have complete and unfettered access to Bell = UNIX code at least circa 32V. Not sure if the licensing allowed for source= -code cross-talk between USG/USL UNIX source and Berkeley, but I remember r= eading somewhere that CSRG students and faculty avoided commercial UNIX lik= e the plague, going so far as to not even look at the literature to see wha= t changes occurred since 32V. Anywho just some thoughts, I find the realm of reverse engineering and re-i= mplementation fascinating, and am always interested in this sort of discuss= ion. - Matt G. P.S. Don't want to derail the thread with this, unless it's deemed worthy a= ddition, but feel free to email privately. Does anyone know if there was a= "formal" PDP-11 and/or VAX disassembler produced by Bell? I know there wa= s one floating around the "user maintained" utilities at some point, I reca= ll seeing a note in a manual saying something to the effect "Rumor has it t= here is a PDP-11 disassembler" but I'm curious if such tools were ever prov= ided in any sort of official capacity. I've been doing some research on wh= at RE tools people had on hand at the time, think "objdump" from GNU binuti= ls.