From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752940AbdLSQCM (ORCPT <rfc822;w@1wt.eu>);
        Tue, 19 Dec 2017 11:02:12 -0500
Received: from bombadil.infradead.org ([65.50.211.133]:35279 "EHLO
        bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751297AbdLSQCI (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 19 Dec 2017 11:02:08 -0500
Date: Tue, 19 Dec 2017 17:01:55 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Zhang Rui <rui.zhang@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>, linux-x86 <x86@kernel.org>,
        Len Brown <len.brown@intel.com>, "Chen, Yu C" <yu.c.chen@intel.com>
Subject: Re: Regression: unable to boot after commit bd9240a18edf ("x86/apic:
 Add TSC_DEADLINE quirk due to errata") - Surface Pro 4 SKL
Message-ID: <20171219160155.zgu5clv5mj2l4aaj@hirez.programming.kicks-ass.net>
References: <20171128081440.mi3nrhxgori75cbs@hirez.programming.kicks-ass.net>
 <1511857335.2498.22.camel@intel.com>
 <alpine.DEB.2.20.1711281023490.1723@nanos>
 <1511866741.2441.5.camel@intel.com>
 <20171128123607.fmgpq76brf6bdkk4@hirez.programming.kicks-ass.net>
 <1511966690.2750.9.camel@intel.com>
 <20171218202822.juwyxsd7millme7o@hirez.programming.kicks-ass.net>
 <1513680504.2569.1.camel@intel.com>
 <20171219152307.ugmlynst574wsdne@hirez.programming.kicks-ass.net>
 <1513698161.2745.14.camel@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <1513698161.2745.14.camel@intel.com>
User-Agent: NeoMutt/20170609 (1.8.3)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, Dec 19, 2017 at 11:42:41PM +0800, Zhang Rui wrote:
> On Tue, 2017-12-19 at 16:23 +0100, Peter Zijlstra wrote:

> > [    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl)
> > [    0.000000] ACPI: IRQ0 used by override.
> > 
> > So your ACPI table has an override for IRQ2 and routes it to IRQ0.

^ this

> >  The HPET document says:
> > 
> >   If the ENABLE_CNF bit and the LEG_RT_CNF bit are both set, then the
> >   interrupts will be routed as follows:
> > 
> >     Timer 0 will be routed to IRQ0 in Non-APIC or IRQ2 in the I/O APIC
> 
> But AFAICS, the HPET emulated timer interrupts goes to IRQ0

Right, so see that ACPI override, that routes I/O APIC IRQ2 to IRQ0, or
it _should_.

Clearly something is messed up here.. but I've no idea what. That whole
IRQ routing stuff is confusing.