Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756957Ab2B2XCe (ORCPT ); Wed, 29 Feb 2012 18:02:34 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:49082 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756841Ab2B2XCd (ORCPT ); Wed, 29 Feb 2012 18:02:33 -0500 From: "Rafael J. Wysocki" To: Randy Dunlap Subject: Re: [PATCH] PCI / PCIe: Introduce command line option to disable ARI Date: Thu, 1 Mar 2012 00:06:33 +0100 User-Agent: KMail/1.13.6 (Linux/3.3.0-rc5+; KDE/4.6.0; x86_64; ; ) Cc: Jesse Barnes , LKML , linux-pci@vger.kernel.org References: <201202292309.42051.rjw@sisk.pl> <4F4EA7B1.9060607@xenotime.net> In-Reply-To: <4F4EA7B1.9060607@xenotime.net> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201203010006.33723.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4086 Lines: 110 On Wednesday, February 29, 2012, Randy Dunlap wrote: > On 02/29/2012 02:09 PM, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki > > > > There are PCIe devices on the market that report ARI support but > > then fail to initialize correctly when ARI is actually used. This > > leads to situations in which kernels 2.6.34 and newer fail to handle > > systems where the previous kernels worked without any apparent > > problems. Unfortunately, it is currently unknown how many such > > devices are there. > > > > For this reason, introduce a new kernel command line option, > > pci=noari, allowing users to disable PCIe ARI altogether if they > > see problems with PCIe device initialization. > > > > Signed-off-by: Rafael J. Wysocki > > --- > > drivers/pci/pci.c | 7 ++++++- > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > Index: linux/drivers/pci/pci.c > > =================================================================== > > --- linux.orig/drivers/pci/pci.c > > +++ linux/drivers/pci/pci.c > > @@ -94,6 +94,9 @@ u8 pci_cache_line_size; > > */ > > unsigned int pcibios_max_latency = 255; > > > > +/* If set, the PCIe ARI capability will not be used. */ > > +static bool pcie_ari_disabled; > > > Please update Documentation/kernel-parameters.txt . Ah, sorry for the omission, updated patch follows. Thanks, Rafael --- From: Rafael J. Wysocki Subject: PCI / PCIe: Introduce command line option to disable ARI There are PCIe devices on the market that report ARI support but then fail to initialize correctly when ARI is actually used. This leads to situations in which kernels 2.6.34 and newer fail to handle systems where the previous kernels worked without any apparent problems. Unfortunately, it is currently unknown how many such devices are there. For this reason, introduce a new kernel command line option, pci=noari, allowing users to disable PCIe ARI altogether if they see problems with PCIe device initialization. Signed-off-by: Rafael J. Wysocki --- Documentation/kernel-parameters.txt | 1 + drivers/pci/pci.c | 7 ++++++- 2 files changed, 7 insertions(+), 1 deletion(-) Index: linux/drivers/pci/pci.c =================================================================== --- linux.orig/drivers/pci/pci.c +++ linux/drivers/pci/pci.c @@ -94,6 +94,9 @@ u8 pci_cache_line_size; */ unsigned int pcibios_max_latency = 255; +/* If set, the PCIe ARI capability will not be used. */ +static bool pcie_ari_disabled; + /** * pci_bus_max_busnr - returns maximum PCI bus number of given bus' children * @bus: pointer to PCI bus structure to search @@ -1922,7 +1925,7 @@ void pci_enable_ari(struct pci_dev *dev) u16 flags, ctrl; struct pci_dev *bridge; - if (!pci_is_pcie(dev) || dev->devfn) + if (pcie_ari_disabled || !pci_is_pcie(dev) || dev->devfn) return; pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI); @@ -3718,6 +3721,8 @@ static int __init pci_setup(char *str) pci_realloc(); } else if (!strcmp(str, "nodomains")) { pci_no_domains(); + } else if (!strncmp(str, "noari", 5)) { + pcie_ari_disabled = true; } else if (!strncmp(str, "cbiosize=", 9)) { pci_cardbus_io_size = memparse(str + 9, &str); } else if (!strncmp(str, "cbmemsize=", 10)) { Index: linux/Documentation/kernel-parameters.txt =================================================================== --- linux.orig/Documentation/kernel-parameters.txt +++ linux/Documentation/kernel-parameters.txt @@ -2111,6 +2111,7 @@ bytes respectively. Such letter suffixes on: Turn ECRC on. realloc reallocate PCI resources if allocations done by BIOS are erroneous. + noari do not use PCIe ARI. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power Management. -- 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/