Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754754Ab0H3JKk (ORCPT ); Mon, 30 Aug 2010 05:10:40 -0400 Received: from david.siemens.de ([192.35.17.14]:24636 "EHLO david.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750867Ab0H3JKj (ORCPT ); Mon, 30 Aug 2010 05:10:39 -0400 Message-ID: <4C7B7572.3070406@siemens.com> Date: Mon, 30 Aug 2010 11:10:10 +0200 From: Jan Kiszka User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 MIME-Version: 1.0 To: Zachary Amsden CC: "kvm@vger.kernel.org" , Avi Kivity , Marcelo Tosatti , Glauber Costa , Thomas Gleixner , John Stultz , "linux-kernel@vger.kernel.org" Subject: Re: [KVM timekeeping 13/35] Perform hardware_enable in CPU_STARTING callback References: <1282291669-25709-1-git-send-email-zamsden@redhat.com> <1282291669-25709-14-git-send-email-zamsden@redhat.com> <4C77E89E.3040106@siemens.com> <4C784DB8.5090105@redhat.com> In-Reply-To: <4C784DB8.5090105@redhat.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1750 Lines: 47 Zachary Amsden wrote: > On 08/27/2010 06:32 AM, Jan Kiszka wrote: >> Zachary Amsden wrote: >> >>> The CPU_STARTING callback was added upstream with the intention >>> of being used for KVM, specifically for the hardware enablement >>> that must be done before we can run in hardware virt. It had >>> bugs on the x86_64 architecture at the time, where it was called >>> after CPU_ONLINE. The arches have since merged and the bug is >>> gone. >>> >> What bugs are you referring to, or since which kernel version is >> CPU_STARTING usable for KVM? I need to encode this into kvm-kmod. >> > > Prior to the x86_64 / i386 merge, CPU_STARTING didn't work the same way > / exist in the x86_64 code... most of this is historical guesswork. At > some point, the 32/64 versions of the code in smpboot.c got merged and > now it does. > > Binary searching around my tree shows this timeframe: > > 2.6.11? - 2.6.23 : silver age ; i386 and x86_64 merge underway > | > 2.6.24 : bronze age ; i386 and x86_64 deprecated > | > 2.6.26 : iron age; smpboot_32.c / smpboot_64.c merge > \ > 2.6.28 : CPU_STARTING exists and first used > > /me scratches head wondering how this affects operation on older kernels.... I basically need to revert your patch on host kernels without CPU_STARTING and also on those where it might be broken. So I will set the barrier to 2.6.28 then. Thanks, Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- 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/