Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932270Ab0F3VcY (ORCPT ); Wed, 30 Jun 2010 17:32:24 -0400 Received: from terminus.zytor.com ([198.137.202.10]:46034 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932087Ab0F3VcW (ORCPT ); Wed, 30 Jun 2010 17:32:22 -0400 Message-ID: <4C2BB7C0.9040000@zytor.com> Date: Wed, 30 Jun 2010 14:31:44 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.10) Gecko/20100621 Fedora/3.0.5-1.fc13 Thunderbird/3.0.5 MIME-Version: 1.0 To: Andrew Morton CC: mingo@redhat.com, linux-kernel@vger.kernel.org, djwong@us.ibm.com, muli@il.ibm.com, cschultz@linux.vnet.ibm.com, stable@kernel.org, tglx@linutronix.de, mingo@elte.hu, linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/urgent] x86, Calgary: Increase max PHB number References: <20100624212647.GI15515@tux1.beaverton.ibm.com> <20100629155151.7caaff4b.akpm@linux-foundation.org> In-Reply-To: <20100629155151.7caaff4b.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2140 Lines: 62 On 06/29/2010 03:51 PM, Andrew Morton wrote: > On Fri, 25 Jun 2010 15:29:50 GMT > "tip-bot for Darrick J. Wong" wrote: > >> Commit-ID: 499a00e92dd9a75395081f595e681629eb1eebad >> Gitweb: http://git.kernel.org/tip/499a00e92dd9a75395081f595e681629eb1eebad >> Author: Darrick J. Wong >> AuthorDate: Thu, 24 Jun 2010 14:26:47 -0700 >> Committer: Ingo Molnar >> CommitDate: Fri, 25 Jun 2010 16:14:58 +0200 >> >> x86, Calgary: Increase max PHB number > > arch/x86/kernel/pci-calgary_64.c: In function 'calgary_init_one': > arch/x86/kernel/pci-calgary_64.c:1059: warning: comparison is always false due to limited range of data type > > from > > BUG_ON(dev->bus->number >= MAX_PHB_BUS_NUM); > > with > > http://userweb.kernel.org/~akpm/stuff/config-akpm2.txt This comes from: /* * The maximum PHB bus number. * x3950M2 (rare): 8 chassis, 48 PHBs per chassis = 384 * x3950M2: 4 chassis, 48 PHBs per chassis = 192 * x3950 (PCIE): 8 chassis, 32 PHBs per chassis = 256 * x3950 (PCIX): 8 chassis, 16 PHBs per chassis = 128 */ #define MAX_PHB_BUS_NUM 384 Clearly there can't be 384 busses with standard PCI numbering (bus numbers are 8 bits). That means either that the number 384 is just wrong, or it means that there are multiple PCI domains involved, and that the BUG_ON() should be something else. Furthermore, in get_tce_space_from_tar() we have: for (bus = 0; bus < MAX_PHB_BUS_NUM; bus++) { struct calgary_bus_info *info = &bus_info[bus]; unsigned short pci_device; u32 val; val = read_pci_config(bus, 0, 0, 0); pci_device = (val & 0xFFFF0000) >> 16; ... which assumes the bus is a PCI bus number, no domain involved. Does this mean the limit should be 256 (in which case we can just drop the BUG_ON()), or is there support for domains which should be in this code but isn't? -hpa -- 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/