From owner-freebsd-arch@FreeBSD.ORG Sat Apr 2 08:00:34 2011 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5B8AA1065678; Sat, 2 Apr 2011 08:00:34 +0000 (UTC) (envelope-from perryh@pluto.rain.com) Received: from agora.rdrop.com (agora.rdrop.com [IPv6:2607:f678:1010::34]) by mx1.freebsd.org (Postfix) with ESMTP id 3C7418FC1C; Sat, 2 Apr 2011 08:00:34 +0000 (UTC) Received: from agora.rdrop.com (66@localhost [127.0.0.1]) by agora.rdrop.com (8.13.1/8.12.7) with ESMTP id p3280XYW036537 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Sat, 2 Apr 2011 01:00:33 -0700 (PDT) (envelope-from perryh@pluto.rain.com) Received: (from uucp@localhost) by agora.rdrop.com (8.13.1/8.12.9/Submit) with UUCP id p3280X74036536; Sat, 2 Apr 2011 01:00:33 -0700 (PDT) Received: from fbsd61 by pluto.rain.com (4.1/SMI-4.1-pluto-M2060407) id AA14774; Fri, 1 Apr 11 23:50:49 PST Date: Sat, 02 Apr 2011 00:50:29 -0700 From: perryh@pluto.rain.com To: m.e.sanliturk@gmail.com Message-Id: <4d96d545.e/wWTIUATgk2CGjt%perryh@pluto.rain.com> References: <4D95E162.40605@FreeBSD.org> <4D95ECDE.1020504@FreeBSD.org> In-Reply-To: User-Agent: nail 11.25 7/29/05 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: freebsd-hackers@freebsd.org, avg@freebsd.org, freebsd-arch@freebsd.org Subject: Re: looking for error codes X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 02 Apr 2011 08:00:34 -0000 Mehmet Erol Sanliturk wrote: > For a long time I am thinking to obtain a physically ( not only > software ) based [read-only] FreeBSD edition by re-arranging some > parts of it , but I do not know how to do it ... > After some years , MFM hard disks abandoned in favor of IDE > ( Integrated Drive Electronics ) hard disks by moving controller > to hard disk and eliminating use of add-on cards with a very > unfortunate design decision as ( a write protect mechanism by > a switch on the hard disks are not implemented ) . At least some IDE drives have write-protect jumpers, which could presumably be replaced with connections to switches. > With respect to my knowledge , no one of the operating systems > has a facility to separate read-only and modifiable parts ... SunOS 4 had a partial solution to this, by rearranging the FS layout so that /usr could be mounted read-only (and often, from a server -- IIRC a single /usr could be shared among multiple diskless clients). They used quite a few symlinks so that things could be found in their accustomed places although actually located elsewhere. The scheme was fairly well described in the SunOS 4 manual set; granted _finding_ a SunOS 4 manual set these days may be a challenge :)