From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/14868 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: [PATCH] remaining steps for time64 switchover Date: Sun, 27 Oct 2019 00:26:45 -0400 Message-ID: <20191027042645.GX16318@brightrain.aerifal.cx> References: <20191021024643.GA6192@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="86858"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Mutt/1.5.21 (2010-09-15) To: musl@lists.openwall.com Original-X-From: musl-return-14884-gllmg-musl=m.gmane.org@lists.openwall.com Sun Oct 27 05:27:00 2019 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by blaine.gmane.org with smtp (Exim 4.89) (envelope-from ) id 1iOa8q-000MSx-FV for gllmg-musl@m.gmane.org; Sun, 27 Oct 2019 05:27:00 +0100 Original-Received: (qmail 17815 invoked by uid 550); 27 Oct 2019 04:26:58 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 17795 invoked from network); 27 Oct 2019 04:26:57 -0000 Content-Disposition: inline In-Reply-To: <20191021024643.GA6192@brightrain.aerifal.cx> Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:14868 Archived-At: On Sun, Oct 20, 2019 at 10:46:43PM -0400, Rich Felker wrote: > demonstrably working). The one omission I'm aware of is what to do > with struct utmpx, which is not actually used at present in any libc > interfaces and thus not part of the ABI surface of libc. That will be > addressed in a separate thread. Or here. So, the story on utmpx: we can either 1. match the current size on 32-bit archs, but move the timeval to unused space at the end where a time64 version fits, or 2. match the current size and layout of the 64-bit struct, making it possible to share records between 32- and 64-bit processes on the same machine. Keep in mind that this struct is not used anywhere in libc presently, but normally it's used as a format for on-disk records. I'm kinda leaning towards option 2, but being that I don't use (and hate) utmp, I'd rather hear opinions from people who do use it. Either way time fields in existing data will break, so it's a question of whether that one-time breakage is already sufficient to go a bit further and get 32/64 compat afterwards. Rich