From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephane Eranian Subject: Re: Info: mapping multiple BARs. Your kernel is fine. Date: Sun, 16 Mar 2014 14:08:16 +0100 Message-ID: References: <20140224162400.GE16457@pd.tnic> <4205942.Tp8ltEsv6e@vostro.rjw.lan> <20140316115546.GA11935@nazgul.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-oa0-f41.google.com ([209.85.219.41]:38946 "EHLO mail-oa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750899AbaCPNIR (ORCPT ); Sun, 16 Mar 2014 09:08:17 -0400 Received: by mail-oa0-f41.google.com with SMTP id j17so4599656oag.0 for ; Sun, 16 Mar 2014 06:08:16 -0700 (PDT) In-Reply-To: <20140316115546.GA11935@nazgul.tnic> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Borislav Petkov Cc: "Rafael J. Wysocki" , lkml , x86 , Bjorn Helgaas , Linux PCI , ACPI Devel Maling List , Zhang Rui , Yinghai Lu , "H. Peter Anvin" Rafael, Thanks for the analysis. On Sun, Mar 16, 2014 at 12:55 PM, Borislav Petkov wrote: > On Sat, Mar 15, 2014 at 03:15:04PM +0100, Rafael J. Wysocki wrote: >> I've just gone throught this. > > Thanks. > >> So the problem is that we have the PNP "system" driver whose only purpose seems >> to be to reserve system resources so that the PCI layer doesn't assign them to >> new devices on hotplug (disclaimer: I didn't invent it, I only read the code and >> comments in there). >> >> It does that for ACPI device objects having the "PNP0C02" and "PNP0C01" IDs. > > Right, pnp 00:01 is PNP0C02. > >> Apparently, snb_uncore_imc_init_box() steps on a range already reserved by that >> driver on your box. And this doesn't seem to be a coincidence, because the ACPI >> device object in question probably *does* correspond to the memory controller >> that the uncore driver attempts to use. >> >> I'm not sure how to address that right now to be honest. Arguably, the PNP >> "system" driver should be replaced with something saner, but still the >> resources it claims need to be kept out of reach of the PCI's resource >> allocation code. > > Well, I'm only conjecturing here but there should be a way for the > uncore code to tell the PNP "system" driver to free this resource > because uncore is going to use it now. Or something to that effect. > I agree. The snb_uncore_imc() is making real (good) use of the device. It needs to own it. So we need a way to free the resource from the PNP system or a way to tell PNP need to grab it on systems with the snb_uncore_imc() support. Does that kind of API exist? Where do I look to prevent PNP from grabbing the IMC?