From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp11.migadu.com ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms5.migadu.com with LMTPS id KHDXHGDPl2LbIgAAbAwnHQ (envelope-from ) for ; Wed, 01 Jun 2022 22:43:12 +0200 Received: from aspmx1.migadu.com ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp11.migadu.com with LMTPS id 0OS/HGDPl2LCZQEA9RJhRA (envelope-from ) for ; Wed, 01 Jun 2022 22:43:12 +0200 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx1.migadu.com (Postfix) with ESMTPS id 420D545512 for ; Wed, 1 Jun 2022 22:43:12 +0200 (CEST) Received: from localhost ([::1]:54624 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nwVBP-000731-7x for larch@yhetil.org; Wed, 01 Jun 2022 16:43:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54710) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nwV9x-0006Ql-Si for guix-devel@gnu.org; Wed, 01 Jun 2022 16:41:42 -0400 Received: from mx1.riseup.net ([198.252.153.129]:53932) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nwV9j-0003Xf-Dd; Wed, 01 Jun 2022 16:41:41 -0400 Received: from fews2.riseup.net (fews2-pn.riseup.net [10.0.1.84]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "mail.riseup.net", Issuer "R3" (not verified)) by mx1.riseup.net (Postfix) with ESMTPS id 4LD1Jg3cq8zDqhV; Wed, 1 Jun 2022 20:41:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=riseup.net; s=squak; t=1654116083; bh=Oi0hGYrbnF6MEgPOLEksVXoGGDQ3uQPdmh1Z6CwX7Os=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=jxc99ZDvwMw5fGuykpkQOYWCfCoc7XvfX1q7mjNujFE3LDnWfsUawnvJ2CXu/jYSW OelX4AtMWDYzAOY7AvJF/KQPM/GYIE0Decde1fyf2XSUjH688sZakeAG8ZYMzFDU6f VJHK6t4bH9HVnI98h6aV201CUBpWmXru1eoks3rE= X-Riseup-User-ID: FBCBA669D13892C3FCE78D60F03BB89717C4BB0A7996B65D9BFBB7D8C13DB102 Received: from [127.0.0.1] (localhost [127.0.0.1]) by fews2.riseup.net (Postfix) with ESMTPSA id 4LD1Jf0HXBz20bf; Wed, 1 Jun 2022 13:41:21 -0700 (PDT) Date: Wed, 1 Jun 2022 22:41:13 +0200 From: raingloom To: Maxime Devos Cc: Ludovic =?UTF-8?B?Q291cnTDqHM=?= , Felix Lechner , Guix Devel Subject: Re: A corner case of broken reproducibility Message-ID: <20220601224113.52e92744@riseup.net> In-Reply-To: <6b761f22d333b0acd21f407a9f5f529aaa8b16d5.camel@telenet.be> References: <87leuj108h.fsf@gnu.org> <31d13a6014b14c886686bca833d926604ce3379d.camel@telenet.be> <87bkvcuynd.fsf@gnu.org> <6b761f22d333b0acd21f407a9f5f529aaa8b16d5.camel@telenet.be> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=198.252.153.129; envelope-from=raingloom@riseup.net; helo=mx1.riseup.net X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: guix-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+larch=yhetil.org@gnu.org Sender: "Guix-devel" X-Migadu-Flow: FLOW_IN X-Migadu-To: larch@yhetil.org X-Migadu-Country: US ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1654116192; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post:dkim-signature; bh=KHSK8Impsnv8eA8XeBrJjHIxwiFQdcxd49I7K3AQwuY=; b=FJjXWFv2NtalsJuBeD+EUIhYrNNpZAew0ad8ZzwY4RvR2qXLdow/qPJ3YV/h8kcI7vHnN6 bItkjI+nH20GFR1L9spfVjSNidbXN3RVuiGkKiIO+JTUE+WjdU1uYZZIDLr/gH9ZDSF8Hv TbPr13aUOiB3OjLLywi9Tnqv/P5/5MPM3OXCoahCcQ5A7SH3B0pgYG+FhEJUkQXzYLva/B P0tn+xVmMJs1eWZFsyCUyXOoHa1JM5vp8JFjjv0BAxp4kcyoAum2mz/Fsrlr4HKdg7iaPW //LxJbTjesR67Q17rKLDPQa9K9rH/cFCoqJ9E4BorbuiMKXrsqTy9jcVlJFtuA== ARC-Seal: i=1; s=key1; d=yhetil.org; t=1654116192; a=rsa-sha256; cv=none; b=NUFHNCdGJbQl9ECM1kIhCmiy+c7yNRkzQe7mKJ/1VvVAe6udMQuZUnRZ6gL++F1/6TVf49 58GSM4WwA4FIDtQP4rtxSwQJiYpsU1wzwjw8tB0ydPjh/YoYdFdHT/gp5db46gRAZW13o/ HyV3JWYkWp7MJZmmTzDGw8URbTg9KgRqlSsd7SKGhhEqXx+gITaCUMznsvdxKOHXkWW/Df CCbTmGFRIfi04B5DpSVEHU0jcH482zbdvNrZjXuXMqlZitMCS/z0SmRYOdGdrPT4AiaO2V sxmpL/zxKAXVosdGs1ROgImcs0P28VjAXXH5bWSHm7wf2Sw4XevAj17ugIekPw== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=riseup.net header.s=squak header.b=jxc99ZDv; dmarc=pass (policy=none) header.from=riseup.net; spf=pass (aspmx1.migadu.com: domain of "guix-devel-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="guix-devel-bounces+larch=yhetil.org@gnu.org" X-Migadu-Spam-Score: -7.43 Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=riseup.net header.s=squak header.b=jxc99ZDv; dmarc=pass (policy=none) header.from=riseup.net; spf=pass (aspmx1.migadu.com: domain of "guix-devel-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="guix-devel-bounces+larch=yhetil.org@gnu.org" X-Migadu-Queue-Id: 420D545512 X-Spam-Score: -7.43 X-Migadu-Scanner: scn0.migadu.com X-TUID: Bbv8hU1CpVqa On Wed, 01 Jun 2022 22:09:11 +0200 Maxime Devos wrote: > Ludovic Court=C3=A8s schreef op wo 01-06-2022 om 18:38 [+0200]: > > There=E2=80=99s a talk by Lennart Poettering where he explains that, > > contrary to what one might think, =E2=80=9Cchown -R $HOME=E2=80=9D turn= s out to be > > fast enough that systemd-homed can do that unconditionally (off the > > of my head). =20 >=20 > Interesting. > Taking "find $HOME > /dev/null" as an approximation of how long "chown > -R $HOME" would take: >=20 > $ time find . > /dev/null=20 >=20 > real 0m7,066s > user 0m0,427s > sys 0m1,341s >=20 > Assuming that =E2=80=98unconditionally =3D only chown -R $HOME if the uid= of > $HOME isn't what was expected=E2=80=99 (otherwise, +7sec for every boot), > that's not too bad. >=20 > That's on a SSD and not a hard disk though, I'd image it would be > worse on a hard disk. >=20 > Depending on the size of $HOME, it could be a lot longer though: >=20 > $ time find /gnu/store > /dev/null=20 >=20 > real 1m9,729s > user 0m4,135s > sys 0m13,840s >=20 > Might still be acceptable as long as uids aren't switched too often > ... >=20 > Can we, as-is in Guix, assume we can modify /home/foo though? E.g. > what if it's put on a separate storage medium not attached at boot. >=20 > Greetings, > Maxime. Could we instead check for existing homes and set uids in /etc/passwd based on that instead? That's practically O(1), but is a bit more involved.