From owner-freebsd-current Tue Apr 18 12:09:04 1995 Return-Path: current-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id MAA14975 for current-outgoing; Tue, 18 Apr 1995 12:09:04 -0700 Received: from halloran-eldar.lcs.mit.edu (halloran-eldar.lcs.mit.edu [18.26.0.159]) by freefall.cdrom.com (8.6.10/8.6.6) with SMTP id MAA14961 for ; Tue, 18 Apr 1995 12:08:53 -0700 Received: by halloran-eldar.lcs.mit.edu; id AA00747; Tue, 18 Apr 1995 15:08:34 -0400 Date: Tue, 18 Apr 1995 15:08:34 -0400 From: Garrett Wollman Message-Id: <9504181908.AA00747@halloran-eldar.lcs.mit.edu> To: "Rodney W. Grimes" Cc: current@FreeBSD.org Subject: Memory fill patterns In-Reply-To: <199504152313.QAA05625@gndrsh.aac.dev.com> References: <636.797979286@freefall.cdrom.com> <199504152313.QAA05625@gndrsh.aac.dev.com> Sender: current-owner@FreeBSD.org Precedence: bulk < said: > We have lots of choices, a grep of /usr/share/dict/words turns > up 64 words that are 8 characters long using the letters [a-filo]. You > use 1 for i and l and 0 for o: [list deleted] Unfortunately, Rod missed the point, or rather, he saw one of them and missed the rest. Here is the rationale for the choice of 0xdeadbeef (or 0xdeadbee1): 1) When printed in decimal, it's obnoxiously large and negative. 2) When printed in hex, It's recognizable. 3) When printed as a float, it's either invalid or at least obnoxiously large. 4) When used as an address, it's unlikely to be mapped. 5) When used as an address, it will cause an unaligned-access trap. This is from memory after someone posted in alt.folklore.computers three or four years ago about the origin of 0xdeadbee1. -GAWollman -- Garrett A. Wollman | Shashish is simple, it's discreet, it's brief. ... wollman@lcs.mit.edu | Shashish is the bonding of hearts in spite of distance. Opinions not those of| It is a bond more powerful than absence. We like people MIT, LCS, ANA, or NSA| who like Shashish. - Claude McKenzie + Florent Vollant