From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e36.co.us.ibm.com (e36.co.us.ibm.com [32.97.110.154]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e36.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 80AE2DDDFE for ; Wed, 20 Dec 2006 15:15:14 +1100 (EST) Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e36.co.us.ibm.com (8.13.8/8.12.11) with ESMTP id kBK4FB1F028659 for ; Tue, 19 Dec 2006 23:15:11 -0500 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.6/8.13.6/NCO v8.1.1) with ESMTP id kBK4FBew504620 for ; Tue, 19 Dec 2006 21:15:11 -0700 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id kBK4FB6b025074 for ; Tue, 19 Dec 2006 21:15:11 -0700 Message-ID: <4588B89E.3090900@us.ibm.com> Date: Tue, 19 Dec 2006 20:14:22 -0800 From: Haren Myneni MIME-Version: 1.0 To: Giuliano Pochini Subject: Re: 2 CPUs, but only one is used References: <20061217144127.579f01f0.pochini@shiny.it> <20061220003545.7053b05c.pochini@shiny.it> In-Reply-To: <20061220003545.7053b05c.pochini@shiny.it> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Giuliano Pochini wrote: >On Sun, 17 Dec 2006 14:41:27 +0100 >Giuliano Pochini wrote: > > > >>I have a dual G4 MDD mac running linux 2.6.19. When I boot with maxcpus=1 and >>then I issue "echo 1 >/sys/devices/system/cpu/cpu1/online" the second CPU is >>put online without errors, but it stays idle+wait=100% and of course >>user+system+nice=0%. It works fine without maxcpus=1. No problems with 2.6.18. >> >>I saw that there are some cpu hotplug related changes in 2.6.19, but I have >>no access to a non-ppc dual cpu box to check if the problem also affects >>other architectures right now. >> >> > >I tried to reproduce the problem on an intel box, but I couldn't. /sys >contains only the cpu0 file if it boots with maxcpus=1. > > On powerpc, when maxcpus=1 is passed, it does not reflect that change in cpu_possible_map. This possible bitmap is created based on device-tree. Where as on i386, it does. I.e, cpu_possible_map contains only one cpu. /sys entries will be created based on cpu_possible_map (I think). Hence, you noticed only cpu0 entry on Intel box. - Haren > >-- >Giuliano. >_______________________________________________ >Linuxppc-dev mailing list >Linuxppc-dev@ozlabs.org >https://ozlabs.org/mailman/listinfo/linuxppc-dev > >