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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 D7EADC433ED for ; Fri, 14 May 2021 17:36:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6FCA613C8 for ; Fri, 14 May 2021 17:36:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233655AbhENRhd (ORCPT ); Fri, 14 May 2021 13:37:33 -0400 Received: from terminus.zytor.com ([198.137.202.136]:56311 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231849AbhENRhc (ORCPT ); Fri, 14 May 2021 13:37:32 -0400 Received: from tazenda.hos.anvin.org ([IPv6:2601:646:8602:8be0:7285:c2ff:fefb:fd4]) (authenticated bits=0) by mail.zytor.com (8.16.1/8.15.2) with ESMTPSA id 14EHa2me3150421 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Fri, 14 May 2021 10:36:02 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 14EHa2me3150421 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2021042801; t=1621013763; bh=sz5jkjvMgb5V+JAn9gd2Tb1fSB3vWOyxs+Bvq6ZrCvE=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=kTSrLr1+lF7XDQSL31hJsRtYDkJWw2YU6shJw0j9SaSDZIuUeFKMsgxBC5jC1cYId y6IdnDXkuVnhmgqWYWtFNMMJv94s6ZzUd1y4zIenuOh2d0AOz0OgtachRtwJXu9qn6 UdXWa2LCJGcTEJSpBVZ/YAJNGfpN0o4XjvnlP65TOeKALa4XHUGgEI+vD8pexNksw8 Ka6iudGeCDMT3Gb9uwO6wabYVUUZAtrJjXFnPhcztcWhQelO2DiL6O+B+k6sO/1Yma t15M29Qxyl1c6fxMoLGHO+6IPDOP4oUN5cpqt0ihng/2SsfpJidLHwy/mU83EW4tn/ Zk+YkegxPwhFg== Subject: Re: [PATCH] x86/i8259: Work around buggy legacy PIC To: Thomas Gleixner , Maximilian Luz , Sachi King , Ingo Molnar , Borislav Petkov , David Laight Cc: "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" References: <20210512210459.1983026-1-luzmaximilian@gmail.com> <3034083.sOBWI1P7ec@yuki> <5c08541a-2615-f075-a189-0462f1005007@gmail.com> <87im3l43w9.ffs@nanos.tec.linutronix.de> From: "H. Peter Anvin" Message-ID: Date: Fri, 14 May 2021 10:35:57 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <87im3l43w9.ffs@nanos.tec.linutronix.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/14/21 10:32 AM, Thomas Gleixner wrote: > > That's a valid assumption. As I said, we can make IOAPIC work even w/o > PIC. I'll have a look how much PIC assumptions are still around. > As far as I read, the problem isn't actually the absence of a PIC (we definitely boot systems without PICs all the time now), but rather that the PIC is advertised in ACPI but is buggy or absent; a similar platform with different firmware doesn't have problem. If my understanding of the thread is correct, it's quirk fodder. -hpa