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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 C5C6CC43462 for ; Fri, 14 May 2021 13:45:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6CC06145A for ; Fri, 14 May 2021 13:45:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231314AbhENNqN (ORCPT ); Fri, 14 May 2021 09:46:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230363AbhENNqL (ORCPT ); Fri, 14 May 2021 09:46:11 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09CF6C061574; Fri, 14 May 2021 06:45:00 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1620999897; 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: in-reply-to:in-reply-to:references:references; bh=Jjy0U9TVSgQ/UDMCkhIERPIDzus1fWQqGP32JHzOO1I=; b=UtuaPgWzO9zfB6iMIFwhPWSqmMP5wvuBvHYlkcATekBDoPJhOYyPA6DnQNHpYy3/2CwUCv XQVhWwlwYeLmJ3QSE6ifWg2N+8Ma9QmzTsYXLsdXjtf0SefxKd4++Nzuul1hTnZp6HwzDX LLKl18SMYDjhGdFPhz4a4CJ5A/sp+wPAuUvIGYTGgk7nTdkQVnO+LNd7rXqzGCBkHhlmGR SzKnN3xpu2oM6pi/HhDG37ABJzvDYs6ux7bz30XOq4tkFel08QPdX+VOU8ENcyKipMSIQj +aDaMg5qe25R/phsxd4fAsIjAmUN3s9zf0rMr8E/jnHEYR52Xof8TdrWHiDdeA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1620999897; 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: in-reply-to:in-reply-to:references:references; bh=Jjy0U9TVSgQ/UDMCkhIERPIDzus1fWQqGP32JHzOO1I=; b=rs/WfdhwubkjY+Ynk5qqlultcDtj9/9JGaGu2UoAIC7NiYbmVKUd3R59P5tMLig6m9mZDf eBSyIwyuWUCPfTBw== To: Maximilian Luz , David Laight , Ingo Molnar , Borislav Petkov Cc: "H. Peter Anvin" , Sachi King , "x86\@kernel.org" , "linux-kernel\@vger.kernel.org" , "stable\@vger.kernel.org" Subject: Re: [PATCH] x86/i8259: Work around buggy legacy PIC In-Reply-To: References: <20210512210459.1983026-1-luzmaximilian@gmail.com> <9b70d8113c084848b8d9293c4428d71b@AcuMS.aculab.com> Date: Fri, 14 May 2021 15:44:57 +0200 Message-ID: <87r1i94eg6.ffs@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Max, On Thu, May 13 2021 at 12:11, Maximilian Luz wrote: > And lastly, if that's any help at all: The PIC device is described in > ACPI in [3]. The Surface Laptop 3 also has an AMD CPU (although a prior > generation) and has the PIC described in the exact same way (can also be > found in that repository), but doesn't exhibit that behavior (and > doesn't show the "Using NULL legacy PIC" line). I expect there's not > much you can change to that definition so that's probably irrelevant > here. > > Again, I don't really know anything about these devices, so my guess > would be bad hardware revision or bad firmware revision. All I know is > that retrying seems to "fix" it. That might be a a power optimization thing. Except for older systems the PIC is not really required for IOAPiC to work. But there is some historical code which makes assumptions. We can change that, but that needs some careful thoughts. Thanks, tglx