From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 14 May 2001 11:53:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 14 May 2001 11:53:20 -0400 Received: from munchkin.spectacle-pond.org ([209.192.197.45]:44037 "EHLO munchkin.spectacle-pond.org") by vger.kernel.org with ESMTP id ; Mon, 14 May 2001 11:53:03 -0400 Date: Mon, 14 May 2001 11:33:45 -0400 From: Michael Meissner To: John Kodis , linux-kernel@vger.kernel.org Subject: Re: Not a typewriterg Message-ID: <20010514113345.B10909@munchkin.spectacle-pond.org> In-Reply-To: <200105140103.f4E13U3r010249@sleipnir.valparaiso.cl> <20010514103148.B9532@tux.gsfc.nasa.gov> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20010514103148.B9532@tux.gsfc.nasa.gov>; from kodis@mail630.gsfc.nasa.gov on Mon, May 14, 2001 at 10:31:48AM -0400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 14, 2001 at 10:31:48AM -0400, John Kodis wrote: > On Sun, May 13, 2001 at 09:03:30PM -0400, Horst von Brand wrote: > > > The old C compiler/old Unix linker guaranteed 6 chars in an external symbol > > name only, and C functions got an underscore prepended: _creat. I guess > > this is the reason for this wart. As to why 6 chars only, I'd guess some > > data structure in the linker was laid out that way. Machines had a few > > dozen Kbs of RAM then, space was precious. > > I recall that RSX-11 and a few other series of early DEC operating > systems stored linker symbols in a "RAD50" encoding scheme which > allowed 6 chararacters to be crammed into a 32-bit "long word". I > suspect that this is where the limitation originated. More trivia. Rad50 actually allows 5 characters per 32-bit word. The 50 is actually 050 in octal (ie, 40 decimal), and allows you to have all 26 english letters, 10 digits, a null, and 3 characters. At this stage, I don't remember what the precise encoding is, or what the additional 3 characters were (I suspect different systems used different characters). One of the first systems I worked on professionally (Data General RDOS) used RAD50 in their object file format. -- Michael Meissner, Red Hat, Inc. (GCC group) PMB 198, 174 Littleton Road #3, Westford, Massachusetts 01886, USA Work: meissner@redhat.com phone: +1 978-486-9304 Non-work: meissner@spectacle-pond.org fax: +1 978-692-4482