From owner-freebsd-toolchain@freebsd.org Mon Mar 30 06:18:59 2020 Return-Path: Delivered-To: freebsd-toolchain@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 186FA275106 for ; Mon, 30 Mar 2020 06:18:59 +0000 (UTC) (envelope-from pjfloyd@wanadoo.fr) Received: from mailman.nyi.freebsd.org (unknown [127.0.1.3]) by mx1.freebsd.org (Postfix) with ESMTP id 48rMjW2xF0z4M0h for ; Mon, 30 Mar 2020 06:18:55 +0000 (UTC) (envelope-from pjfloyd@wanadoo.fr) Received: by mailman.nyi.freebsd.org (Postfix) id 0D9E3275101; Mon, 30 Mar 2020 06:18:45 +0000 (UTC) Delivered-To: toolchain@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 01831275100 for ; Mon, 30 Mar 2020 06:18:44 +0000 (UTC) (envelope-from pjfloyd@wanadoo.fr) Received: from smtp.smtpout.orange.fr (smtp04.smtpout.orange.fr [80.12.242.126]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (Client CN "Bizanga Labs SMTP Client Certificate", Issuer "Bizanga Labs CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 48rMj54Nkhz4Lt7 for ; Mon, 30 Mar 2020 06:18:32 +0000 (UTC) (envelope-from pjfloyd@wanadoo.fr) Received: from garrigue.home ([2.7.71.138]) by mwinf5d39 with ME id LWJ82200E2z0Kde03WJ8tX; Mon, 30 Mar 2020 08:18:09 +0200 X-ME-Helo: garrigue.home X-ME-Auth: cGpmbG95ZEB3YW5hZG9vLmZy X-ME-Date: Mon, 30 Mar 2020 08:18:09 +0200 X-ME-IP: 2.7.71.138 From: Paul Floyd Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.80.23.2.2\)) Subject: x86 process memory map Message-Id: Date: Mon, 30 Mar 2020 08:18:08 +0200 To: "toolchain@freebsd.org" X-Mailer: Apple Mail (2.3608.80.23.2.2) X-Rspamd-Queue-Id: 48rMj54Nkhz4Lt7 X-Spamd-Bar: +++ Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of pjfloyd@wanadoo.fr has no SPF policy when checking 80.12.242.126) smtp.mailfrom=pjfloyd@wanadoo.fr X-Spamd-Result: default: False [3.38 / 15.00]; FREEMAIL_FROM(0.00)[wanadoo.fr]; MV_CASE(0.50)[]; RECEIVED_SPAMHAUS_PBL(0.00)[138.71.7.2.khpj7ygk5idzvmvt5x4ziurxhy.zen.dq.spamhaus.net : 127.0.0.11]; MIME_TRACE(0.00)[0:+]; R_DKIM_NA(0.00)[]; FREEMAIL_ENVFROM(0.00)[wanadoo.fr]; ASN(0.00)[asn:3215, ipnet:80.12.240.0/20, country:FR]; MID_RHS_MATCH_FROM(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; ARC_NA(0.00)[]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; IP_SCORE(0.00)[ip: (2.78), ipnet: 80.12.240.0/20(1.59), asn: 3215(2.63), country: FR(0.00)]; DMARC_NA(0.00)[wanadoo.fr]; AUTH_NA(1.00)[]; RCPT_COUNT_ONE(0.00)[1]; NEURAL_SPAM_MEDIUM(0.98)[0.983,0]; RCVD_TLS_LAST(0.00)[]; NEURAL_SPAM_LONG(1.00)[0.999,0]; RCVD_IN_DNSWL_NONE(0.00)[126.242.12.80.list.dnswl.org : 127.0.5.0]; TO_DN_EQ_ADDR_ALL(0.00)[]; R_SPF_NA(0.00)[]; IP_SCORE_FREEMAIL(0.00)[]; RWL_MAILSPIKE_POSSIBLE(0.00)[126.242.12.80.rep.mailspike.net : 127.0.0.17]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-toolchain@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Maintenance of FreeBSD's integrated toolchain List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Mar 2020 06:18:59 -0000 When I run procstat on a small 32bit app that just calls sleep (on = FreeBSD 12.1 amd64) then I see at the end of the map 22353 0xfbffe000 0xfffde000 --- 0 0 0 0 ----- = --=20 22353 0xfffde000 0xffffe000 rw- 3 3 1 0 ---D- = df=20 22353 0xffffe000 0xfffff000 r-x 1 1 94 0 ----- = ph I think the last block is for signal handlers and the last but one block = is the user stack. But what is between 0xfbffe000 and 0xfffde000? It's a bit less than = 64Mbytes. This has no protection flags, no resident pages or references = and no type. My guess is that this is some sort of guard page for the = user stack. Can anyone confirm this? Also, does anyone know if this has been present = in FreeBSD for a long time? My copy of =E2=80=9CThe Design and = Implementation of FreeBSD" 2e doesn't show anything between stack and = shared libraries. A+ Paul