Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757347Ab0F3Vp2 (ORCPT ); Wed, 30 Jun 2010 17:45:28 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:53132 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756811Ab0F3Vp0 (ORCPT ); Wed, 30 Jun 2010 17:45:26 -0400 Date: Wed, 30 Jun 2010 14:45:05 -0700 From: "Darrick J. Wong" To: "H. Peter Anvin" Cc: Andrew Morton , mingo@redhat.com, linux-kernel@vger.kernel.org, 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 Message-ID: <20100630214505.GO15515@tux1.beaverton.ibm.com> Reply-To: djwong@us.ibm.com References: <20100624212647.GI15515@tux1.beaverton.ibm.com> <20100629155151.7caaff4b.akpm@linux-foundation.org> <4C2BB7C0.9040000@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C2BB7C0.9040000@zytor.com> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2700 Lines: 71 On Wed, Jun 30, 2010 at 02:31:44PM -0700, H. Peter Anvin wrote: > 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? Yes, it should be 256. Some time ago there was talk of building 8-node x3950M2s with PCI domain support, but the final word now is that nobody will ever have more than 4 nodes. The BUG_ON can be dropped, too. I'll send a patch shortly that incorporates both updates. (Honestly I sort of wonder if the Calgary code should be removed entirely, but that's a whole different battle....) --D -- 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/