From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932448Ab1BWTQq (ORCPT ); Wed, 23 Feb 2011 14:16:46 -0500 Received: from kroah.org ([198.145.64.141]:35878 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932440Ab1BWTQp (ORCPT ); Wed, 23 Feb 2011 14:16:45 -0500 Date: Wed, 23 Feb 2011 11:16:17 -0800 From: Greg KH To: Thomas Gleixner Cc: KY Srinivasan , "gregkh@suse.de" , "linux-kernel@vger.kernel.org" , "virtualization@lists.osdl.org" , "devel@linuxdriverproject.org" Subject: Re: [PATCH]: Staging: hv: Allocate the vmbus irq dynamically Message-ID: <20110223191617.GC1030@kroah.com> References: <1297799735-25917-1-git-send-email-kys@microsoft.com> <6E21E5352C11B742B20C142EB499E048011738@TK5EX14MBXC124.redmond.corp.microsoft.com> <6E21E5352C11B742B20C142EB499E048011787@TK5EX14MBXC124.redmond.corp.microsoft.com> <6E21E5352C11B742B20C142EB499E04801191C@TK5EX14MBXC124.redmond.corp.microsoft.com> <6E21E5352C11B742B20C142EB499E048013C67@TK5EX14MBXC128.redmond.corp.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 21, 2011 at 03:51:56PM +0100, Thomas Gleixner wrote: > On Mon, 21 Feb 2011, KY Srinivasan wrote: > > > > > There are various ways to solve that proper. > > > > > > > > > > - You can provide the interrupt number from ACPI/PCI or whatever your HV > > > > > provides as enumeration. > > > > > > > > > > - Use a fixed vector like XEN does for the event channel > > > > > > > > > > - Use dynamic allocation in the IOAPIC space like the kernel does for > > > > > MSI(-X) > > > > > > > > > > Thanks, > > > > > > > > > > tglx > > > > > > > > I am not claiming that what I have done here is the best possible solution. > > > > However, I will submit to you that it is better than what we had here > > > > prior to this patch. I will address this and a whole lot of other issues > > > > in future patches. > > > > > > No, it's _NOT_ better in any way. You trade breaking your PV thing > > > against breaking random other drivers. Care to explain why you think > > > that's better ? > > > > The root device for the VM is bound to the PV driver on some distributions. > > So, if we cannot load the PV drivers, we do not have a system that boots. > > In general, the system performance without these PV drivers is so poor that > > for all practical purposes, having the PV drivers is almost a requirement > > for having a useable system. While the platform supports configuration of the VM with > > some emulated devices, it is not a recommended configuration (because of > > performance reasons) for Linux virtual machines on the Hyper-V platform. > > It does not matter whether it's recommended or not. If it results in a > non usable emulated device it's broken. Just imagine you grab the > serial interrupt, which results in not having a debug console. Not at > all acceptable. > > > I have spent significantly more time debating this patch than > > developing this patch that I still think improves the current > > driver. I will leave it to Greg and other powers that be to decide > > if this patch will be accepted. Let me know what your verdict is. > > As I said, any other clean solution (and I pointed out 3) over this > hack. I agree, KY, please fix this up properly, I've dropped this patch from my queue now. thanks, greg k-h