Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934876AbcLUPnz (ORCPT ); Wed, 21 Dec 2016 10:43:55 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:47437 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933440AbcLUPnx (ORCPT ); Wed, 21 Dec 2016 10:43:53 -0500 Date: Wed, 21 Dec 2016 07:43:48 -0800 From: Christoph Hellwig To: Paolo Bonzini Cc: Christoph Hellwig , Roman Kagan , Stephen Hemminger , Radim =?utf-8?B?S3LEjW3DocWZ?= , "K. Y. Srinivasan" , Vitaly Kuznetsov , kvm@vger.kernel.org, "Denis V . Lunev" , Haiyang Zhang , x86@kernel.org, linux-kernel@vger.kernel.org, Ingo Molnar , "H. Peter Anvin" , devel@linuxdriverproject.org, Thomas Gleixner Subject: Re: [PATCH 12/15] hyperv: move VMBus connection ids to uapi Message-ID: <20161221154348.GA31401@infradead.org> References: <20161220155602.6298-1-rkagan@virtuozzo.com> <20161220155602.6298-13-rkagan@virtuozzo.com> <20161220092543.6183bffd@xeon-e3> <20161221062939.GB15917@rkaganb.sw.ru> <20161221121858.GA17429@infradead.org> <20161221125920.GG15917@rkaganb.sw.ru> <20161221142654.GB8594@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.1 (2016-04-27) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 582 Lines: 12 On Wed, Dec 21, 2016 at 04:39:18PM +0100, Paolo Bonzini wrote: > That said, there are precedents in using UAPI this way for PV > interfaces. See for example include/uapi/linux/virtio*.h and > arch/x86/include/uapi/asm/kvm_para.h. We have all kinds of historical examples, but most of them turned into a major pain sooner or later - my favourite example are the SCSI protocol headers. Protocols needs to stay compatible on the (virtual) wire, but not on the language level. Locking us into the strict UABI policies for them just make someone life horrible further down the road.