From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-x434.google.com (mail-wr1-x434.google.com [IPv6:2a00:1450:4864:20::434]) by sourceware.org (Postfix) with ESMTPS id 5E6CB3858D3C for ; Fri, 11 Nov 2022 10:25:15 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 5E6CB3858D3C Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=linuxfoundation.org Received: by mail-wr1-x434.google.com with SMTP id l14so5893676wrw.2 for ; Fri, 11 Nov 2022 02:25:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=google; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:cc:to:from:subject:message-id:from:to:cc:subject :date:message-id:reply-to; bh=cxvZocW4H1LEbnKMnkchetyEyaAmgEEobBC5Shw089E=; b=dJRlBGlRpW+nrJsO4IRJwdvcnHv9Do3ZpJAq5LjInHg9dBXrwkMJ81XtdN+o32vOA8 AxA4GgAvgiAerC7NsA05nfak+mUvxAyG/w253RpxEDvTP7INEx7ISoyovjPYgESkB4gR a8TYdO+XJDXvlYo3ZQ5A2ces8M/PIY+VClYFU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:cc:to:from:subject:message-id:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=cxvZocW4H1LEbnKMnkchetyEyaAmgEEobBC5Shw089E=; b=qZ6RO8nb5gcry92h+9TbmnlLFRCoPBZQc3rCZiFZbmPdz98fOOaSUj5eOL+d40cV49 voDG0k8BrEoGzIk1OeYV7HHHEhc+ZPW5fy3w7KHxBy52Aw/a0RgQzmQk30dYhiekBCGl 1PjZXNBQi4zSpBU9QCOGmdiOpubIRaCOHhGNBwfKVn9ylymKsVATp+tSxFPdXa5O1ISN d6I7CdOVquy+dWw5jk1at/nbcM/C7UU86lHMoQkWPM+saqBHQX9NEKMlP3ypdRIBFvyx JPpgZVfJR4vvOMMHraxkOBXGNEW26ew83ieyuzfuK+PA0bfBqY9Bwt0kFqf0Ap51KUzF 0ANg== X-Gm-Message-State: ANoB5pkk2cj8t5JhoQEpca396du/xM/Cx8F5ux/+rAkyaMg35En8QWtV NsgFZUwsB+yOGrwI/w4r++Squw== X-Google-Smtp-Source: AA0mqf4qk2H/ieyO1dHpKSLlkg9NRsUiQ3ZFEff9K2VYekCjgnWy5WuckmJbH/6rbZuCrnigLI71fA== X-Received: by 2002:adf:f4c9:0:b0:236:562b:f67a with SMTP id h9-20020adff4c9000000b00236562bf67amr809217wrp.562.1668162314241; Fri, 11 Nov 2022 02:25:14 -0800 (PST) Received: from ?IPv6:2001:8b0:aba:5f3c:2115:4271:c44b:61ee? ([2001:8b0:aba:5f3c:2115:4271:c44b:61ee]) by smtp.gmail.com with ESMTPSA id n18-20020a7bcbd2000000b003cf9bf5208esm7811441wmi.19.2022.11.11.02.25.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Nov 2022 02:25:13 -0800 (PST) Message-ID: <2dc4de1101546506c60f0a7253e71b26760ae53a.camel@linuxfoundation.org> Subject: Re: On time64 and Large File Support From: Richard Purdie To: Sam James , Carlos O'Donell via Libc-alpha , autoconf@gnu.org Cc: c-std-porting@lists.linux.dev, Zack Weinberg , David Seifert , Gentoo Toolchain , Arsen =?UTF-8?Q?Arsenovi=C4=87?= , Paul Eggert Date: Fri, 11 Nov 2022 10:25:11 +0000 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.4-0ubuntu1 MIME-Version: 1.0 X-Spam-Status: No, score=-3.9 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Fri, 2022-11-11 at 08:38 +0000, Sam James wrote: > In Gentoo, we've been planning out what we should do for time64 on glibc = [0] > and concluded that we need some support in glibc for a newer option. I'll= outline > why below. >=20 > Proposal: glibc gains two new build-time configure options: > * --enable-hard-time64 > * --enable-hard-lfs >=20 > These would hard-enable the relevant #defines within glibc's headers and = ensure that any > binaries built with such a glibc have both Large File Support (LFS) and t= ime64 support. >=20 > I've come to the conclusion it's infeasible to try handle the migration p= iecemeal. Various > mismatches can and will occur (and while it's more likely with time64, it= 's possible with LFS > too) [1]. As a data point, Yocto Project has been debating this a bit. Based upon what I've seen so far, I reached a similar conclusion, that we probably needed to "just switch". As a source based system, the situation is quite different to distros with binary feeds though. My questions are around how much warning we can give people where code is doing something it shouldn't and I don't have a good feel for how much risk we're putting onto users with existing runtimes. Cheers, Richard