From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Graf Subject: Re: [PULL 33/41] KVM: PPC: Book3S: Move KVM_REG_PPC_WORT to an unused register number Date: Fri, 30 May 2014 17:58:13 +0200 Message-ID: <5388AA95.8050003@suse.de> References: <1401453776-55285-1-git-send-email-agraf@suse.de> <1401453776-55285-34-git-send-email-agraf@suse.de> <5388A8DF.9050300@redhat.com> <5388A996.8010606@suse.de> <5388A9F6.5090301@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, mtosatti@redhat.com, Paul Mackerras To: Paolo Bonzini , kvm-ppc@vger.kernel.org Return-path: Received: from cantor2.suse.de ([195.135.220.15]:38309 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965054AbaE3P6P (ORCPT ); Fri, 30 May 2014 11:58:15 -0400 In-Reply-To: <5388A9F6.5090301@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 30.05.14 17:55, Paolo Bonzini wrote: > Il 30/05/2014 17:53, Alexander Graf ha scritto: >>> This is an ABI break, this symbol was added in 3.14. I think I should >>> revert this. Can you convince me otherwise? >> >> There's nothing bad happening with the change. Newer user space won't be >> able to read WORT on older kernels, but there were more things broken >> that just WORT for POWER8 support there ;). >> >> And user space build with new headers running on an old kernel won't >> find the register, which is OK. > > Would new userspace with old kernel be able to detect that POWER8 > support isn't quite complete? It couldn't, no. It would try to run a guest - if it happens to work we're lucky ;). Even then the only thing that would remotely be affected by that one_reg rename is live migration (which just got a few more fixes in this pull request). Alex