From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1947451Ab3BHX5a (ORCPT ); Fri, 8 Feb 2013 18:57:30 -0500 Received: from mail-wg0-f44.google.com ([74.125.82.44]:52352 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1947361Ab3BHX53 (ORCPT ); Fri, 8 Feb 2013 18:57:29 -0500 MIME-Version: 1.0 In-Reply-To: References: <20130204184436.GA13256@gmail.com> <20130204191408.GA32081@kroah.com> <20130204191334.GB14837@gmail.com> <20130207080236.ae38366537cf3f13b9668606@canb.auug.org.au> <20130206214646.GA28135@gmail.com> <20130208084029.d7d97d6e26580a5512712f91@canb.auug.org.au> <20130208145539.GC30334@gmail.com> Date: Sat, 9 Feb 2013 01:57:27 +0200 X-Google-Sender-Auth: jzoHIQii9iBOZNOSAJJz9dS7irY Message-ID: Subject: Re: kvmtool tree (Was: Re: [patch] config: fix make kvmconfig) From: Pekka Enberg To: Linus Torvalds Cc: Ingo Molnar , Stephen Rothwell , David Rientjes , Greg Kroah-Hartman , Sasha Levin , Randy Dunlap , David Woodhouse , Michal Marek , "H. Peter Anvin" , Thomas Gleixner , "H. Peter Anvin" , Linux Kernel Mailing List Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus, I'm going to go out on a limb here and say that this might the odd out case that's not really supposed to happen where *you* are just WRONG, CRAZY, and IGNORING REALITY. On Fri, Feb 8, 2013 at 11:14 PM, Linus Torvalds wrote: > I think merging it would be an active mistake, and would just tie two > projects together that just shouldn't be tied together. The two are already tied together - that was the whole premise of the project! What Ingo proposed two years ago was to implement a (simple) userspace counterpart of KVM under tools/kvm using kernel development process and reusing kernel code as much as possible. He predicted that we'd eventually have: - a clean codebase that's accessible to new developers - new kernel features developed in 'lock-step' with the userspace code - encouraged kernel developers to write userspace code As it turns out, Ingo's predictions were correct. We support KVM on ARMv8 even before the in-kernel code has hit mainline. People implemented vhost drivers in lock-step. Most of the contributors are also kernel developers. And we in fact have a clean codebase that's accessible to anyone who knows the kernel coding style. I honestly don't see any of these things happening had we not taken the path suggested by Ingo early on. On Fri, Feb 8, 2013 at 11:14 PM, Linus Torvalds wrote: > The fact that kvmtool isn't available as a standalone project probably > keeps people actively from using it. You can't just fetch kvmtool. You > have to fetch the kernel and kvmtool, and if you're a kernel developer > you either have to make a whole new kernel tree for it (which is > stupid) or merge it into your normal kernel tree that has development > that has nothing to do with kvmtool (which is stupid AND F*CKING > INSANE) Actually, as a kernel developer, you don't need to do that. You can 'make install' from a kvmtool branch and leave it at that - just like with perf. [ And if it was in your tree, you'd wouldn't even need the branch ;-). ] And yes, you are absolutely correct that living in the kernel tree is suboptimal for the casual user. However, it's a trade-off to make tools/kvm *development* easier especially when you need to touch both kernel and userspace code. On Fri, Feb 8, 2013 at 11:14 PM, Linus Torvalds wrote: > "git" is a hell of a lot more useful utility for kernel development, > to the point that practically we couldn't do without it any more, and > it isn't merged into the kernel. It's a separate project with a > separate life, and it is *better* for it. Sure but the difference between "git" and kvmtool is that a significant chuck of kvmtool development is directly related to in-kernel KVM and device drivers. That's why I've argued from day one that tools/kvm is 'special'. Pekka