From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757174AbXD0UC5 (ORCPT ); Fri, 27 Apr 2007 16:02:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757179AbXD0UC4 (ORCPT ); Fri, 27 Apr 2007 16:02:56 -0400 Received: from hu-out-0506.google.com ([72.14.214.229]:46262 "EHLO hu-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757174AbXD0UCy (ORCPT ); Fri, 27 Apr 2007 16:02:54 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:date:from:to:cc:subject:message-id:references:mime-version:content-type:content-disposition:content-transfer-encoding:in-reply-to:user-agent; b=WzPcYpKL+nUtH0CmuGE4mO7ewjtTyFnGtdPYkjokuDuSYwRUNhsd17Auwng+ifWImLFOS9nHNdltYRJP3Uf8jsc37OEzCu2VymYALrZHG2hQQsZzi+r4cFfpSs9lTo7AWoLKq3iUL8lIoccn9Jkc7niz3+/mTQcDVgDwNOGyQok= Date: Fri, 27 Apr 2007 22:02:47 +0200 From: Luca Tettamanti To: Miguel Ojeda Cc: linux-kernel@vger.kernel.org, oliver pinter , Robert Hancock , Roman Zippel Subject: Re: [BUG? -rc7] SMP: Just one CPU activated: P4 3GHz HT Message-ID: <20070427200247.GA7270@dreamland.darkstar.lan> References: <462BF4DF.7080401@shaw.ca> <653402b90704230111p50b72586te73c1288f12a0079@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <653402b90704230111p50b72586te73c1288f12a0079@mail.gmail.com> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Il Mon, Apr 23, 2007 at 10:11:52AM +0200, Miguel Ojeda ha scritto: > On 4/22/07, Luca Tettamanti wrote: > >Probably the two siblings are enumerated only in ACPI tables. If you > >disable ACPI the kernel won't be aware of the second "core". > > > >Luca > >-- > >"Su cio` di cui non si puo` parlare e` bene tacere". > > Ludwig Wittgenstein > > > > On 4/23/07, Robert Hancock wrote: > > > >You didn't enable ACPI, it's needed for almost all systems to detect HT > >and also for many systems to detect multi-cores as well. > > > >Aside from that, in general I would say that on any modern x86 system > >ACPI should always be enabled. In many cases it seems the BIOS code is > >not tested much without ACPI anymore, so going without ACPI can be > >problematic. > > > >-- > >Robert Hancock Saskatoon, SK, Canada > >To email, remove "nospam" from hancockr@nospamshaw.ca > >Home Page: http://www.roberthancock.com/ > > > > > > Thanks all of you. It seems the problem is ACPI, however, should not > it be noted in some way? Maybe at Documentation/smp.txt, maybe at the > help section at CONFIG_SMP, maybe a "depends on ..." > > Or maybe CONFIG_SMP should enable some bits of the ACPI code needed to > detect such additional cores. "depends on" is too strong. There exists architecture without ACPI but with SMP support; even in the x86 world a number of systems still support both MPS and ACPI. Mentioning it in the help text should be enough. Roman, are you in charge for the KConfig files? --- SMP support in modern systems often relies on ACPI being active; add a couple of lines in the help text for CONFIG_SMP Signed-Off-By: Luca Tettamanti --- arch/i386/Kconfig | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig index 53d6237..48ef899 100644 --- a/arch/i386/Kconfig +++ b/arch/i386/Kconfig @@ -111,6 +111,9 @@ config SMP Y to "Enhanced Real Time Clock Support", below. The "Advanced Power Management" code will be disabled if you say Y here. + Note that ACPI is often required to support newer multi-core CPUs + and HT on Intel P4 processors. + See also the , , and the SMP-HOWTO available at Luca -- "Vorrei morire ucciso dagli agi. Vorrei che di me si dicesse: ``Com'è morto?'' ``Gli è scoppiato il portafogli''" -- Marcello Marchesi