From owner-freebsd-current Wed Sep 2 00:17:07 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id AAA02437 for freebsd-current-outgoing; Wed, 2 Sep 1998 00:17:07 -0700 (PDT) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from smtp03.primenet.com (smtp03.primenet.com [206.165.6.133]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id AAA02426 for ; Wed, 2 Sep 1998 00:17:05 -0700 (PDT) (envelope-from tlambert@usr02.primenet.com) Received: (from daemon@localhost) by smtp03.primenet.com (8.8.8/8.8.8) id AAA29693; Wed, 2 Sep 1998 00:16:04 -0700 (MST) Received: from usr02.primenet.com(206.165.6.202) via SMTP by smtp03.primenet.com, id smtpd029659; Wed Sep 2 00:15:55 1998 Received: (from tlambert@localhost) by usr02.primenet.com (8.8.5/8.8.5) id AAA22302; Wed, 2 Sep 1998 00:15:51 -0700 (MST) From: Terry Lambert Message-Id: <199809020715.AAA22302@usr02.primenet.com> Subject: Re: ELF binaries size To: jdp@polstra.com (John Polstra) Date: Wed, 2 Sep 1998 07:15:51 +0000 (GMT) Cc: bde@zeta.org.au, reilly@zeta.org.au, current@FreeBSD.ORG In-Reply-To: <199809020221.TAA17213@austin.polstra.com> from "John Polstra" at Sep 1, 98 07:21:07 pm X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > I think it implies that elf wastes a full page of memory (the space > > between the ':'s above) most of the time (unless the ':'s are on a > > page boundary), while aout only wastes an average of half a page > > (the space between the text ':' and the end of the page). > > But a.out has a repeat of the same situation at the juncture of data > and bss, and ELF does not. In the disk image rather than in the memory image. I think Bruce is mistaking the dual mapping for a single mapping, on the theory that in a unified VM and buffer cache, there can be only one instance of a page hung off the VP. Bruce should look at the ELF (and COFF) loaders. > It's moot on the i386, if I remember correctly. Doesn't execute > permission imply read permission on the i386? > > Also, how does it enhance security to prevent a program from reading > its own text segment? If a program doesn't want to read its text > segment then it should simply ... not read it. :-) Good reason to not use an Intel processor... Consider the case of a program of permission --x--x--x... This "security through obscurity" is bogus, in any case. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message