From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp1 ([2001:41d0:2:4a6f::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms11 with LMTPS id qB8/FumjSGCyQwAA0tVLHw (envelope-from ) for ; Wed, 10 Mar 2021 10:48:09 +0000 Received: from aspmx1.migadu.com ([2001:41d0:2:4a6f::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp1 with LMTPS id YEmaEemjSGDtfQAAbx9fmQ (envelope-from ) for ; Wed, 10 Mar 2021 10:48:09 +0000 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 DB4B71922B for ; Wed, 10 Mar 2021 11:48:08 +0100 (CET) Received: from localhost ([::1]:45132 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lJwNs-0003Gv-3R for larch@yhetil.org; Wed, 10 Mar 2021 05:48:08 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:42096) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lJwNi-0003FQ-Fh for guix-devel@gnu.org; Wed, 10 Mar 2021 05:47:58 -0500 Received: from fencepost.gnu.org ([2001:470:142:3::e]:59134) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lJwNi-0002ff-79; Wed, 10 Mar 2021 05:47:58 -0500 Received: from [2a01:e0a:1d:7270:af76:b9b:ca24:c465] (port=48672 helo=ribbon) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1lJwNh-0007sz-OE; Wed, 10 Mar 2021 05:47:58 -0500 From: =?utf-8?Q?Ludovic_Court=C3=A8s?= To: Christopher Baines Subject: Re: Implications of QEMU binfmt transparent emulation for builds References: <87eegsnexv.fsf@cbaines.net> X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: 20 =?utf-8?Q?Vent=C3=B4se?= an 229 de la =?utf-8?Q?R?= =?utf-8?Q?=C3=A9volution?= X-PGP-Key-ID: 0x090B11993D9AEBB5 X-PGP-Key: http://www.fdn.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 3CE4 6455 8A84 FDC6 9DB4 0CFB 090B 1199 3D9A EBB5 X-OS: x86_64-pc-linux-gnu Date: Wed, 10 Mar 2021 11:47:55 +0100 In-Reply-To: <87eegsnexv.fsf@cbaines.net> (Christopher Baines's message of "Sat, 06 Mar 2021 21:35:24 +0000") Message-ID: <87v99z4750.fsf@gnu.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: guix-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: guix-devel@gnu.org Errors-To: guix-devel-bounces+larch=yhetil.org@gnu.org Sender: "Guix-devel" X-Migadu-Flow: FLOW_IN ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1615373289; 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; bh=6zlM5pWFqDrT5xtBKYFexsOP8oKUZmwFBvj3QTOHGBE=; b=qnpgY3aOKGzyIqyhqGzNTUl7s2R4nGUUW2zTqoZrtsxBzTmyWRwql2Udu8FTs6YrF4Bs6q 6efJNtcMGv2G+7USpT6ENWAkpvVh/LeJgzrqUe0lLu7fUery9V7QU5ZY2WVK24zZbw+Mqu P57PtNT2yp8RQkWPr9YBZQWDFOgx6unSshzku+Z/mO8HV6A4pABe+X9MQaj6yAhYyUmYBS 63c1z6tNihuHpn8+MbYienDVIr6OfC7pKudPMJ/+egAd/tg7CdrcrYu/fMKVi2l7RNl1/5 r+jXG0AtZLHBZV/2KMYZlnGi5JNKwzTPWggHHL0ay2AfHLCveQzM+uTSaDEk2A== ARC-Seal: i=1; s=key1; d=yhetil.org; t=1615373289; a=rsa-sha256; cv=none; b=NS4grOJUPjcjwYopEj2AccQuZPwZw0oJ+UM850V5gsga24jlaQ5VIp9jljUtUpIGPM/MDK WsQ94g9GTS3d349lv68StsKENrP1jLaIyBv8zL5Y0M1bdicjjal5rmS5bK5u8b7rNLL2+J HxYeWGzde2cPIxICmh453Pr9UP6GluM1ZYwJEhxUK7+PYRp3n6zAtQhK+wNT+yfaALMfJN lmjaKy505H7Fmj+RWGXs3hxgHDDZG/kl1eefXtc5KemEpnqDs6uWti8zBxayDohoymIaRF 9rudLsJNEQgiIoVFSzb07C36HNrEuoT0m617kYs0nM50W2JjtiW3BzI3Zc7JaQ== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=none; dmarc=pass (policy=none) header.from=gnu.org; spf=pass (aspmx1.migadu.com: domain of guix-devel-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=guix-devel-bounces@gnu.org X-Migadu-Spam-Score: -2.89 Authentication-Results: aspmx1.migadu.com; dkim=none; dmarc=pass (policy=none) header.from=gnu.org; spf=pass (aspmx1.migadu.com: domain of guix-devel-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=guix-devel-bounces@gnu.org X-Migadu-Queue-Id: DB4B71922B X-Spam-Score: -2.89 X-Migadu-Scanner: scn0.migadu.com X-TUID: WVGvTj7fegLb Hi Chris, Christopher Baines skribis: > Anyway, something that's been on my mind regarding QEMU and builds is > how well this matches up with building natively. In particular, I'm > concerned that there are some derivations that will build on system A > with some QEMU configuration allowing binaries for system B to be run, > but won't build if that QEMU support wasn't there. I think there's also > a chance that you could have a derivation for system A that builds on a > system with QEMU support for system B, but then wouldn't build natively > on system B. > > I think the first scenario is more likely, mainly because I wonder if > this happens with cross built packages. If the package attempts to run > software built for the target system, that will work if there's QEMU > support there for that target system, but not if that QEMU support is > lacking. > > This is just a theory at this point, I at least don't know of any cases > of this happening, but I also haven't been looking. Any ideas? We had concrete problems that manifested as CMake failing to find a compiler when running emulated (emulated AArch64/ARMv7 on x86_64), whereas it would find the compiler when running natively: https://issues.guix.gnu.org/43513 That=E2=80=99s the worst case: an issue showing up in emulated builds in a deterministic fashion, and never happening on actual hardware. Thanks, Ludo=E2=80=99.