From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2BDE1A945 for ; Tue, 10 Sep 2024 16:23:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725985420; cv=none; b=EqSxVLVjzqC5XU/NOzVdDHYuunZwBRStNf4hITM9qAfOpRVce0aPwh/pwDAECbSrZMZwW1DusYdN6WYbaW2cesqtNVErE9dmWFHSyWBJ5YYsGS3qej9ODu3TIQ3k5/Ny6+pi5X9IzR8oK2p7KS+1uvyTiehaSdjuPXKuP/tLym8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725985420; c=relaxed/simple; bh=KEpGlZ2NYD1KrnguFedKR/4i1CUoleKImlBUunKGSYI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=CoSnOu78QzQOHqLhoJjf9904Vnz9srrIcr+TDk9tugyd7INX4ONujKn9Fr82wpOx6CHokp6BeVyXwwmMoovmEV262MZFh/sHHvOWWLP/gD/pwSIrhW+QPtuwnqEV9MQVfWf6pMakQ6oqaU10AgPWV9OImTkoUcsnAJ6u4JWWG0Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=fAfyQ6x7; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fAfyQ6x7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1725985418; h=from:from: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; bh=jvuVY+bm3Q6/gQyNXrtl+BuPr2aqHrjKJQQ5tGJvGJs=; b=fAfyQ6x72KNMZC4sjzQ2azHRrOssF9eIAgnIDnYottjsvt9g8Ir7kZ77DFnjqPxHA/4wcI 4Umql1rdF60zlMJckYrlb5s5MPdPjT0j3MN9jS3C7zAv268+IfarbRE8AyTe8NoSO9GKMh rYsmVlko9zKEIakGv7V6XeNkAOLlniM= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-88-PTGy5XF-N2itiCxif2r--A-1; Tue, 10 Sep 2024 12:23:34 -0400 X-MC-Unique: PTGy5XF-N2itiCxif2r--A-1 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E91CC195608B; Tue, 10 Sep 2024 16:23:30 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.2.16.4]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3A7481956048; Tue, 10 Sep 2024 16:23:24 +0000 (UTC) From: Florian Weimer To: Arsen =?utf-8?Q?Arsenovi=C4=87?= via Gcc Cc: Bruno Haible , Arsen =?utf-8?Q?Arsenovi=C4=87?= , "Andreas K. Huettel" , Wookey , Khem Raj , Paul Eggert , libc-alpha@sourceware.org, binutils@sourceware.org, config-patches@gnu.org, distributions@lists.linux.dev, devel@lists.fedoraproject.org, glaubitz@debian.org, maskray@google.com, dickey@invisible-island.net, toolchain@gentoo.org Subject: Re: Proposed CHOST change for the 64bit time_t transition In-Reply-To: <86mskitf0d.fsf@aarsen.me> ("Arsen =?utf-8?Q?Arsenovi=C4=87?= via Gcc"'s message of "Sun, 08 Sep 2024 16:08:02 +0200") References: <4996568.GXAFRqVoOG@noumea> <3848277.MHq7AAxBmi@noumea> <6e8dadbc-7ae2-465f-b8f6-d0d62507a191@cs.ucla.edu> <1868152.c1hCyg87lr@nimes> <86mskitf0d.fsf@aarsen.me> Date: Tue, 10 Sep 2024 18:23:22 +0200 Message-ID: <87a5gfo4ud.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: distributions@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable * Arsen Arsenovi=C4=87 via Gcc: > Bruno Haible writes: > >> Paul Eggert wrote: >>> I'd rather just switch, as Debian has. >> >> I'd go one step further, and not only >> make the ABI transition without changing the canonical triplet, >> but also >> make gcc and clang define -D_FILE_OFFSET_BITS=3D64 -D_TIME_BITS=3D64 >> among their predefines. > > At that point, we should bump SONAME of libc and simply remove 32-bit > time support. This would probably be okay generally. Just doing the > predefine doesn't really fix anything - all the problems of not being > able to detect whether t64 support exists still persist, with no > mechanism to prevent mixing. Defaulting to 64-bit time_t would also make dlsym etc. work again. For post-GLIBC_2.1 targets (where valid binaries are expected to use symbol versioning) it's not absolutely required to do a soname bump, just changing the symbol version baseline should be enough (set DEFAULT to e.g. GLIBC_2.40 in shlib-versions). Old binaries will use __libc_start_main@GLIBC_2.4 or __libc_start_main@GLIBC_2.34, and fail to load. This could be a more source-compatible change becaue I suspect not everyone uses LIBC_SO in to get the soname for libc.so. I do not have a strong opinion whether this should be done for most 32-bit targets. Except for i386, where I think we should aim to preserve compatibility with legacy binaries for many years to come. All these changes have implications for LSB complinace, as people keep reminding us: LoongArch glibc does not provide libutil shared object, against LSB 5.0= =20 But as I explained on the ticket, the way LSB is constructed, it's surprisingly architecture-specific even in its generic parts, and 32-bit Arm with its GLIBC_2.4 baseline won't have the required GLIBC_2.3.4 symbols (such as __chk_fail@GLIBC_2.3.4) anyway. Thanks, Florian