Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932320AbWCEAo1 (ORCPT ); Sat, 4 Mar 2006 19:44:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932314AbWCEAo1 (ORCPT ); Sat, 4 Mar 2006 19:44:27 -0500 Received: from smtp.osdl.org ([65.172.181.4]:4579 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S932312AbWCEAo0 (ORCPT ); Sat, 4 Mar 2006 19:44:26 -0500 Date: Sat, 4 Mar 2006 16:42:38 -0800 From: Andrew Morton To: Dave Jones Cc: 76306.1226@compuserve.com, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, ak@suse.de, Ashok Raj Subject: Re: 2.6.16rc5 'found' an extra CPU. Message-Id: <20060304164238.37d2ea49.akpm@osdl.org> In-Reply-To: <20060302010953.GA19755@redhat.com> References: <200603011957_MC3-1-B99B-8FFE@compuserve.com> <20060302010953.GA19755@redhat.com> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3558 Lines: 99 Dave Jones wrote: > > On Wed, Mar 01, 2006 at 07:55:25PM -0500, Chuck Ebbert wrote: > > In-Reply-To: <20060301230317.GF1440@redhat.com> > > > > On Wed, 1 Mar 2006 18:03:17, Dave Jones wrote: > > > > > (17:59:38:davej@nemesis:~)$ cat /sys/devices/system/cpu/cpu0/topology/core_siblings > > > 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001 > > > (17:59:47:davej@nemesis:~)$ cat /sys/devices/system/cpu/cpu1/topology/core_siblings > > > 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000002 > > > > > > Neither of these CPUs are HT / dual-core, so shouldn't these be the same ? > > > > Those are bitmaps. 1 => only bit 0 is set => CPU 0 is all alone. > > > > Did you really build a 256-CPU SMP kernel or is ACPI ignoring CONFIG_NR_CPUS > > or something? > > Yes, it's =256. > Is that the only way in which to trigger the bug? If so, I'd be inclined to hold the fix back for 2.6.17. From: Ashok Raj Local apic entries are only 8 bits, but it seemed to not be caught with u8 return value result in the check cpu_index >= NR_CPUS becomming always false. drivers/acpi/processor_core.c: In function `acpi_processor_get_info': drivers/acpi/processor_core.c:483: warning: comparison is always false due to limited range of data type Signed-off-by: Ashok Raj Cc: "Brown, Len" Cc: Dave Jones Signed-off-by: Andrew Morton --- drivers/acpi/processor_core.c | 10 +++++----- 1 files changed, 5 insertions(+), 5 deletions(-) diff -puN drivers/acpi/processor_core.c~acpi-signedness-fix-2 drivers/acpi/processor_core.c --- 25/drivers/acpi/processor_core.c~acpi-signedness-fix-2 Fri Mar 3 16:25:09 2006 +++ 25-akpm/drivers/acpi/processor_core.c Fri Mar 3 16:25:09 2006 @@ -382,7 +382,7 @@ static int acpi_processor_remove_fs(stru /* Use the acpiid in MADT to map cpus in case of SMP */ #ifndef CONFIG_SMP -#define convert_acpiid_to_cpu(acpi_id) (0xff) +#define convert_acpiid_to_cpu(acpi_id) (-1) #else #ifdef CONFIG_IA64 @@ -395,7 +395,7 @@ static int acpi_processor_remove_fs(stru #define ARCH_BAD_APICID (0xff) #endif -static u8 convert_acpiid_to_cpu(u8 acpi_id) +static int convert_acpiid_to_cpu(u8 acpi_id) { u16 apic_id; int i; @@ -421,7 +421,7 @@ static int acpi_processor_get_info(struc acpi_status status = 0; union acpi_object object = { 0 }; struct acpi_buffer buffer = { sizeof(union acpi_object), &object }; - u8 cpu_index; + int cpu_index; static int cpu0_initialized; ACPI_FUNCTION_TRACE("acpi_processor_get_info"); @@ -466,7 +466,7 @@ static int acpi_processor_get_info(struc cpu_index = convert_acpiid_to_cpu(pr->acpi_id); /* Handle UP system running SMP kernel, with no LAPIC in MADT */ - if (!cpu0_initialized && (cpu_index == 0xff) && + if (!cpu0_initialized && (cpu_index == -1) && (num_online_cpus() == 1)) { cpu_index = 0; } @@ -480,7 +480,7 @@ static int acpi_processor_get_info(struc * less than the max # of CPUs. They should be ignored _iff * they are physically not present. */ - if (cpu_index >= NR_CPUS) { + if (cpu_index == -1) { if (ACPI_FAILURE (acpi_processor_hotadd_init(pr->handle, &pr->id))) { ACPI_ERROR((AE_INFO, _ - 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/