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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 8E3D5C4741C for ; Sat, 15 Feb 2020 09:25:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6E25E2072D for ; Sat, 15 Feb 2020 09:25:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725963AbgBOJZM (ORCPT ); Sat, 15 Feb 2020 04:25:12 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:56927 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725852AbgBOJZL (ORCPT ); Sat, 15 Feb 2020 04:25:11 -0500 Received: from p5b06da22.dip0.t-ipconnect.de ([91.6.218.34] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1j2th4-0005vn-Gk; Sat, 15 Feb 2020 10:24:58 +0100 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 6270F101161; Sat, 15 Feb 2020 10:24:57 +0100 (CET) From: Thomas Gleixner To: Sean V Kelley , bhelgaas@google.com, corbet@lwn.net, mingo@redhat.com, bp@alien8.de Cc: x86@kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kar.hin.ong@ni.com, sassmann@kpanic.de, Sean V Kelley Subject: Re: [PATCH 0/2] Add boot interrupt quirk mechanism for Xeon chipsets In-Reply-To: <20200214213313.66622-1-sean.v.kelley@linux.intel.com> References: <20200214213313.66622-1-sean.v.kelley@linux.intel.com> Date: Sat, 15 Feb 2020 10:24:57 +0100 Message-ID: <8736bctd7a.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Sean V Kelley writes: > When IRQ lines on secondary or higher IO-APICs are masked (e.g., > Real-Time threaded interrupts), many chipsets redirect IRQs on > this line to the legacy PCH and in turn the base IO-APIC in the > system. The unhandled interrupts on the base IO-APIC will be > identified by the Linux kernel as Spurious Interrupts and can > lead to disabled IRQ lines. > > Disabling this legacy PCI interrupt routing is chipset-specific and > varies in mechanism between chipset vendors and across generations. > In some cases the mechanism is exposed to BIOS but not all BIOS > vendors choose to pick it up. With the increasing usage of RT as it > marches towards mainline, additional issues have been raised with > more recent Xeon chipsets. > > This patchset disables the boot interrupt on these Xeon chipsets where > this is possible with an additional mechanism. In addition, this > patchset includes documentation covering the background of this quirk. Well done! The documentation is really appreciated! Reviewed-by: Thomas Gleixner