Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760918Ab2EKT0l (ORCPT ); Fri, 11 May 2012 15:26:41 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:64553 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932488Ab2EKT0j (ORCPT ); Fri, 11 May 2012 15:26:39 -0400 Date: Fri, 11 May 2012 22:26:31 +0300 From: Ido Yariv To: "H. Peter Anvin" Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Ingo Molnar , Thomas Gleixner , Shai Fultheim Subject: Re: [PATCH v4] vsmp: Fix number of CPUs when vsmp is disabled Message-ID: <20120511192631.GA13342@NoteStation.colubris.lan> References: <20120509082225.GB5036@NoteStation.colubris.lan> <1336552121-6742-1-git-send-email-ido@wizery.com> <20120509154448.GD2653@gmail.com> <4FAA938A.1030003@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FAA938A.1030003@zytor.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4124 Lines: 144 Hi, On Wed, May 09, 2012 at 08:55:54AM -0700, H. Peter Anvin wrote: > On 05/09/2012 08:44 AM, Ingo Molnar wrote: > > > > * Ido Yariv wrote: > > > >> +static void __init vsmp_cap_cpus(void) > >> +{ > >> + void __iomem *address; > >> + unsigned int cfg, topology, node_shift, maxcpus; > >> + > >> +#ifdef CONFIG_X86_VSMP > >> + /* VSMP is enabled, no need to cap cpus */ > >> + return; > >> +#elif defined(CONFIG_SMP) > >> + /* > >> + * CONFIG_X86_VSMP is not configured, so limit the number CPUs to the > > > > I suspect this will throw compiler warnings in the > > CONFIG_X86_VSMP && !CONFIG_SMP case. > > > > What on Earth is the point of allowing that combination? Why not make > X86_VSMP depend on SMP and reduce the testing matrix? CONFIG_X86_VSMP shouldn't be used without CONFIG_SMP, so we can safely add this dependency. Ingo's suggestion will still fix unreferenced variables warnings, so how about the following patch? Thanks, Ido. >From 6fa023be44749092088618379f13d7a3e086d692 Mon Sep 17 00:00:00 2001 From: Shai Fultheim Date: Mon, 16 Apr 2012 10:39:35 +0300 Subject: [PATCH v5] vsmp: Fix number of CPUs when vsmp is disabled In case CONFIG_X86_VSMP is not set, limit the number of CPUs to the number of CPUs of the first board. Also make CONFIG_X86_VSMP depend on CONFIG_SMP, as there's little point in having a vsmp machine with a single CPU. Signed-off-by: Shai Fultheim [ido@wizery.com: rebased, fixed minor coding-style issues] Signed-off-by: Ido Yariv --- arch/x86/Kconfig | 1 + arch/x86/kernel/vsmp_64.c | 40 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+), 0 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index c9866b0..b1e98c9 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -374,6 +374,7 @@ config X86_VSMP select PARAVIRT depends on X86_64 && PCI depends on X86_EXTENDED_PLATFORM + depends on SMP ---help--- Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is supposed to run on these EM64T-based machines. Only choose this option diff --git a/arch/x86/kernel/vsmp_64.c b/arch/x86/kernel/vsmp_64.c index a1d804b..8eeb55a 100644 --- a/arch/x86/kernel/vsmp_64.c +++ b/arch/x86/kernel/vsmp_64.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -22,6 +23,8 @@ #include #include +#define TOPOLOGY_REGISTER_OFFSET 0x10 + #if defined CONFIG_PCI && defined CONFIG_PARAVIRT /* * Interrupt control on vSMPowered systems: @@ -149,12 +152,49 @@ int is_vsmp_box(void) return 0; } #endif + +static void __init vsmp_cap_cpus(void) +{ +#if !defined(CONFIG_X86_VSMP) && defined(CONFIG_SMP) + void __iomem *address; + unsigned int cfg, topology, node_shift, maxcpus; + + /* + * CONFIG_X86_VSMP is not configured, so limit the number CPUs to the + * ones present in the first board, unless explicitly overridden by + * setup_max_cpus + */ + if (setup_max_cpus != NR_CPUS) + return; + + /* Read the vSMP Foundation topology register */ + cfg = read_pci_config(0, 0x1f, 0, PCI_BASE_ADDRESS_0); + address = early_ioremap(cfg + TOPOLOGY_REGISTER_OFFSET, 4); + if (WARN_ON(!address)) + return; + + topology = readl(address); + node_shift = (topology >> 16) & 0x7; + if (!node_shift) + /* The value 0 should be decoded as 8 */ + node_shift = 8; + maxcpus = (topology & ((1 << node_shift) - 1)) + 1; + + pr_info("vSMP CTL: Capping CPUs to %d (CONFIG_X86_VSMP is unset)\n", + maxcpus); + setup_max_cpus = maxcpus; + early_iounmap(address, 4); +#endif +} + void __init vsmp_init(void) { detect_vsmp_box(); if (!is_vsmp_box()) return; + vsmp_cap_cpus(); + set_vsmp_pv_ops(); return; } -- 1.7.6.5 -- 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/