From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752419AbbI3PM3 (ORCPT ); Wed, 30 Sep 2015 11:12:29 -0400 Received: from www.linutronix.de ([62.245.132.108]:39164 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750768AbbI3PM0 (ORCPT ); Wed, 30 Sep 2015 11:12:26 -0400 Date: Wed, 30 Sep 2015 17:11:41 +0200 (CEST) From: Thomas Gleixner To: Denys Vlasenko cc: Ingo Molnar , Jiang Liu , Len Brown , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC] x86: Reduce MAX_LOCAL_APIC and MAX_IO_APICS In-Reply-To: <1443210512-24236-1-git-send-email-dvlasenk@redhat.com> Message-ID: References: <1443210512-24236-1-git-send-email-dvlasenk@redhat.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 25 Sep 2015, Denys Vlasenko wrote: > > +config MAX_LAPIC_ID > + int "Maximum APIC ID" > + range 8 32768 > + default "8" > + ---help--- > + Use this option to set maximum allowed Local APIC ID higher than > + maximum number of CPUs. This may be necessary for machines > + with large number of processor sockets and non-contiguous > + LAPIC numbering. > + This setting will be automatically rounded up, if necessary. This is wrong. If you would limit the APIC IDs then you really break stuff. You can only limit the number of APICs. ACPI: LAPIC (acpi_id[0x00] lapic_id[0x00] enabled) ACPI: LAPIC (acpi_id[0x01] lapic_id[0x02] enabled) And that's not a really large machine.. Thanks, tglx