From owner-cvs-all Sat Dec 12 20:33:26 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id UAA09892 for cvs-all-outgoing; Sat, 12 Dec 1998 20:33:26 -0800 (PST) (envelope-from owner-cvs-all@FreeBSD.ORG) Received: from daphne.bogus (dialup5.black-hole.com [206.145.13.25]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id UAA09882; Sat, 12 Dec 1998 20:33:22 -0800 (PST) (envelope-from hank@black-hole.com) Received: from localhost (hank@localhost) by daphne.bogus (8.9.1/8.8.8) with SMTP id XAA05860; Sat, 12 Dec 1998 23:33:15 -0600 (CST) (envelope-from hank@black-hole.com) X-Authentication-Warning: daphne.bogus: hank owned process doing -bs Date: Sat, 12 Dec 1998 23:33:15 -0600 (CST) From: Henry Miller X-Sender: hank@daphne.bogus Reply-To: Henry Miller To: Dag-Erling Smorgrav cc: Matt Dillon , cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/kern vfs_syscalls.c In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk On 12 Dec 1998, Dag-Erling Smorgrav wrote: > Matt Dillon writes: > Speaking of kernel dumps, what happens to physical memory pages when > they're not in use? Are they zeroed? If not, is it possible to add a > kernel option that zeroes out unused pages, or fills them with a fixed > pattern (e.g. f001f001 og deadbeef)? That would make kernel dumps more > compressible... Woah! When there is a kernel dump, something is wrong. I have seen (not on freebsd, but on other systems) where memory marked free contained the critical clue to why the dump occured. When a kernel dumps we cannot assume that the flags marking memory as free are correct. A system can write to "free" memory intending a different area, not corrupt anything until it goes a little farther and overwrites a different subsystem that executes sometime latter. I don't know how x86 memory protection works, so maybe the above can't happen, but I wouldn't count on it. -- http://blugill.home.ml.org/ hank@black-hole.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message