From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f45.google.com (mail-wr1-f45.google.com [209.85.221.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EFA1220E7 for ; Fri, 11 Nov 2022 10:25:15 +0000 (UTC) Received: by mail-wr1-f45.google.com with SMTP id k8so5903070wrh.1 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=UQPGJqXA9A8yryMhZFDMWxdbQ7ndJu7YdYOlBxzqmcQjOiLy8v0Nqpy8yEVxQ5VAB5 9/igPHtntu3p+vmItTTWBcDgMOA/+WRgxWlknfhaWjmV2YiNjb6vka555QsF4JapLwZf JkHcmUayOqd6uX6BHz6xR8peXvRiZShAQnZ+3hCeCa1syTV51kzGxvOEvLEDsKlscld6 wejOCwcvFQ/P6R6ZIXnR4gF0nvG9a8vt2vuf/A8iBi38zv7o98E5St2KW492V6PyamJ/ OpJKd3C1534maSHotioMXeKwybbsueRRE2SH8etiAHmTf0icak/+pCLhoOdVY54Kjoio RoaA== X-Gm-Message-State: ANoB5plfcwNSjaiAPP8Zw4jp2/9iKWW9y/grCs4L5N0fq4uttefQ/IYU wXvQx2+6qnIHpe8XL7XNULUm5w== 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 Precedence: bulk X-Mailing-List: c-std-porting@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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