From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6F1DC43381 for ; Fri, 8 Mar 2019 00:47:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B89C520675 for ; Fri, 8 Mar 2019 00:47:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726248AbfCHArs convert rfc822-to-8bit (ORCPT ); Thu, 7 Mar 2019 19:47:48 -0500 Received: from linux-libre.fsfla.org ([209.51.188.54]:38844 "EHLO linux-libre.fsfla.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726237AbfCHArs (ORCPT ); Thu, 7 Mar 2019 19:47:48 -0500 Received: from free.home (home.lxoliva.fsfla.org [172.31.160.164]) by linux-libre.fsfla.org (8.15.2/8.15.2/Debian-3) with ESMTP id x280lDiH031397; Fri, 8 Mar 2019 00:47:15 GMT Received: from livre (livre.home [172.31.160.2]) by free.home (8.15.2/8.15.2) with ESMTP id x280kkci391076; Thu, 7 Mar 2019 21:46:46 -0300 From: Alexandre Oliva To: "Maciej W. Rozycki" Cc: Aaro Koskinen , Tom Li , James Hogan , Jiaxun Yang , Huacai Chen , Ralf Baechle , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC] On the Current Troubles of Mainlining Loongson Platform Drivers Organization: Free thinker, not speaking for FSF Latin America References: <20190208083038.GA1433@localhost.localdomain> <20190211125506.GA21280@localhost.localdomain> <20190211230614.GB22242@darkstar.musicnaut.iki.fi> <20190217235951.GA20700@darkstar.musicnaut.iki.fi> Date: Thu, 07 Mar 2019 21:46:46 -0300 In-Reply-To: (Maciej W. Rozycki's message of "Thu, 7 Mar 2019 17:59:42 +0000 (GMT)") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Scanned-By: MIMEDefang 2.84 Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Mar 7, 2019, "Maciej W. Rozycki" wrote: > So this seems backwards to me, port I/O is supposed to be strongly > ordered, so if removing the ordering guarantee "fixes" your problem, then > there must be a second bottom here. Well, it partially restores the earlier state, so the actual bug goes back to latent. We just have to find out what it is. My plan, in the next time slot I can devote to this investigation, is to try to bisect source files that use these interfaces to identify a minimal set that can switch to the new barriers without breaking anything, then report back after failing to make sense of it myself ;-) So, yeah, several more bottoms to dig through. > Does your platform use `war_io_reorder_wmb'? Err... I'm not sure I understand your question. It uses it in __BUILD_IOPORT_SINGLE within the expanded out function, given !barrier, but you already knew that. Did you mean to ask what war_io_reorder_wmb expand to, or whether there are other uses of war_io_reorder_wmb, or what? -- Alexandre Oliva, freedom fighter https://FSFLA.org/blogs/lxo Be the change, be Free! FSF Latin America board member GNU Toolchain Engineer Free Software Evangelist Hay que enGNUrecerse, pero sin perder la terGNUra jamás-GNUChe