Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753046Ab3FZVAX (ORCPT ); Wed, 26 Jun 2013 17:00:23 -0400 Received: from mail-ob0-f169.google.com ([209.85.214.169]:44016 "EHLO mail-ob0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752576Ab3FZVAR (ORCPT ); Wed, 26 Jun 2013 17:00:17 -0400 MIME-Version: 1.0 In-Reply-To: <20130626121757.GP9294@intel.com> References: <1372177330-28013-1-git-send-email-mika.westerberg@linux.intel.com> <1372177330-28013-7-git-send-email-mika.westerberg@linux.intel.com> <20130625141556.2f9de7b1@jbarnes-desktop> <20130626121757.GP9294@intel.com> From: Bjorn Helgaas Date: Wed, 26 Jun 2013 14:59:56 -0600 Message-ID: Subject: Re: [PATCH 6/6] x86/PCI: quirk Thunderbolt PCI-to-PCI bridges To: Mika Westerberg Cc: Jesse Barnes , Greg Kroah-Hartman , "Rafael J. Wysocki" , Yinghai Lu , "Ronciak, John" , "Penner, Miles J" , Bruce Allan , "Kirill A. Shutemov" , Heikki Krogerus , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "x86@kernel.org" , "alex.williamson@redhat.com" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1725 Lines: 41 [+cc Alex] On Wed, Jun 26, 2013 at 6:17 AM, Mika Westerberg wrote: > On Tue, Jun 25, 2013 at 02:15:56PM -0700, Jesse Barnes wrote: >> On Tue, 25 Jun 2013 19:22:10 +0300 >> Mika Westerberg wrote: >> >> > + if (!(pci_probe & PCI_NOASSIGN_ROMS)) { >> > + pr_info("Thunderbolt host router detected disabling ROMs\n"); >> > + pci_probe |= PCI_NOASSIGN_ROMS; >> > + } >> >> I wonder if this should just be the default on x86? Or do we allocate >> ROM space to address some other platform where we need it and the BIOS >> doesn't do it for the devices we care about? > > Good question. In our case it definitely helps to have pci=norom the > default. Can't tell if it might break something that depends on the current > behaviour. I think the current default behavior is that if the BIOS has assigned the ROM BAR, we keep that assignment, and if it hasn't, we allocate MEM space for it. And "pci=norom" means that we don't allocate MEM space for it, even if the BIOS hasn't assigned it. "pci=norom" is only implemented on x86. I think most other arches allocate MEM space for ROMs, with no way to turn that off. PA-RISC seems to ignore ROMs (dino_fixup_bus()), but that looks like the exception. I'm slightly concerned that if we make the x86 default be "never assign space for ROMs unless the BIOS has done it," we might break virtualized guests that need access to ROMs. Alex? Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/