From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS3215 2.6.0.0/16 X-Spam-Status: No, score=-1.0 required=3.0 tests=AWL,BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,RCVD_IN_SBL_CSS,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=no autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [IPv6:2620:52:3:1:0:246e:9693:128c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 2D1D11F8C6 for ; Wed, 18 Aug 2021 16:23:24 +0000 (UTC) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 55BE93969C07 for ; Wed, 18 Aug 2021 16:23:22 +0000 (GMT) Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by sourceware.org (Postfix) with ESMTPS id F2B9A3855038 for ; Wed, 18 Aug 2021 16:22:21 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org F2B9A3855038 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: sourceware.org; spf=none smtp.mailfrom=infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=HwP/nMh1cO8cF7GObYL+nv9FmhI1pvtnORa3FRBGMnE=; b=dRRewrHMhqhelJiynY40+Jt/8X CEXQEFp13ZKVcdj7C+ptF0cC1ssJADzlz1h6gin+O7U+8mzDpwt0p4fDsGKUuspm4w+ndmOlwhElk IDh50Gk8NXoNBZ0hgxx02xW1ZrBn8n5p+GjmjrdPyckwuJ1RXtLCUMmrGBQs3DCEIgqGDNH3cNgt/ vccEXuajJuGJE1wwtPzSz3Xl9xcSxCo9jDFrqm+25yU/Q69SQ+fUnCX+MGxqRppXjmptDurJDgW5N 0ni9VP89jyoJLu7O8BLM7Oq3lYLkw4BJbldk4F8Tl/2NknLBTTPIPJx8bkHiEdIftbwGreIpKAzPp j0A+dhhg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mGOIu-00421p-8q; Wed, 18 Aug 2021 16:20:50 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id C955F981DD4; Wed, 18 Aug 2021 18:20:34 +0200 (CEST) Date: Wed, 18 Aug 2021 18:20:34 +0200 From: Peter Zijlstra To: Thomas Gleixner Subject: Re: [PATCH 2/4] futex2: Implement vectorized wait Message-ID: <20210818162034.GA26408@worktop.programming.kicks-ass.net> References: <20210805190405.59110-1-andrealmeid@collabora.com> <20210805190405.59110-3-andrealmeid@collabora.com> <87v94310gm.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87v94310gm.ffs@tglx> X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Davidlohr Bueso , libc-alpha@sourceware.org, linux-api@vger.kernel.org, Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, Steven Rostedt , Ingo Molnar , mtk.manpages@gmail.com, =?iso-8859-1?Q?Andr=E9?= Almeida , Darren Hart , kernel@collabora.com, krisman@collabora.com Errors-To: libc-alpha-bounces+e=80x24.org@sourceware.org Sender: "Libc-alpha" On Wed, Aug 18, 2021 at 01:00:57PM +0200, Thomas Gleixner wrote: > > +/** > > + * struct futex_waitv - A waiter for vectorized wait > > + * @val: Expected value at uaddr > > + * @uaddr: User address to wait on > > + * @flags: Flags for this waiter > > + */ > > +struct futex_waitv { > > + __u64 val; > > Again. Why u64? So I think the idea was that if we're going to do new syscalls, we should cater for future extentions, one of which was 64bit futexes (for 64bit archs) (along with u{8,16,32}) The previous set of patches implemented a more complete replacement ABI -- which I rather liked, however the implementation was completely disjoint from the existing futexes, which was a non-starter for me. Anyway, yes, current futexes are u32, but if we want to ever do u64 futexes, we should either do this syscall with a u64, or already plan to retire the whole syscall. Obiously this would've made good Changelog material, but alas it wasn't there.