From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Graf Subject: Re: [PATCH] Inform users about busy device assignment attempt Date: Wed, 09 Dec 2009 21:15:16 +0100 Message-ID: <4B200554.1020302@suse.de> References: <1260381853-8954-1-git-send-email-agraf@suse.de> <20091209181956.GA13487@redhat.com> <4B1FF7FD.5080407@suse.de> <20091209194030.GD13487@redhat.com> <4B1FFE06.8090909@suse.de> <20091209201414.GE13487@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: "Daniel P. Berrange" Return-path: Received: from cantor2.suse.de ([195.135.220.15]:43737 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757703AbZLIUPK (ORCPT ); Wed, 9 Dec 2009 15:15:10 -0500 In-Reply-To: <20091209201414.GE13487@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Daniel P. Berrange wrote: > On Wed, Dec 09, 2009 at 08:44:06PM +0100, Alexander Graf wrote: > >> Daniel P. Berrange wrote: >> >>> On Wed, Dec 09, 2009 at 08:18:21PM +0100, Alexander Graf wrote: >>> >>> >>>> Daniel P. Berrange wrote: >>>> >>>> >>>>> Unconditionally telling people to run rmmod is a pretty dangerous thing >>>>> todo. If they typod and gave the PCI addr of their disk controller instead >>>>> of the NIC, they'll be less than happy at the results of our recommended >>>>> command to "fix" the error. Likewise if they have multiple devices using >>>>> the same driver & just want to assign one of them. I think it is safer to >>>>> just have the first bit of your proposed error message >>>>> >>>>> "The device 04:00.0 is in use by the kernel driver 'igb'." >>>>> >>>>> >>>>> NB 'rmmod' is not the ideal approach for PCI assignment. It is better >>>>> to explicitly re-bind the device to 'pcistub' because that ensures that >>>>> no other driver will ever be able to reclaim the device. >>>>> >>>>> >>>>> >>>> Oh - mind to get into detail there? It'd be great if we could tell users >>>> an even better way to unbind their device from the driver than rmmod :) >>>> >>>> >>> The direct low level sysfs way involves the following steps >>> >>> // Tell pci-stub to accept a particular vendor+product ID binding >>> # echo "8086 27cb" > /sys/bus/pci/drivers/pci-stub/new_id >>> >>> // Remove device from existing PCI driver >>> # echo "00:1d.3" > /sys/bus/pci/drivers/e1000/unbind >>> >>> // Add device to pci-stub PCI driver >>> # echo "00:1d.3" > /sys/bus/pci/drivers/pci-stub/bind >>> >>> // Tell pci-stub to stop accepting a vendor+product ID binding >>> # echo "8086 27cb" > /sys/bus/pci/drivers/pci-stub/remove_id >>> >>> The reason for that last step is that if you have multiple devices of >>> the same vendor+product, you don't want a later hotplug event to bind >>> the new device to pci-stub too ! >>> >>> >> So what would you think if we'd just print out those 4 commands to the >> user, so people who don't use libvirt still get guidance when using >> -pcidevice :). They should be fairly easy to construct from the >> information we have. >> > > I think it is better to put that information in the QEMU docs for the > -pcidevice argument where it can be properly explained in detail, > outlining the potential consequences of the actions. The error message > could direct people to the docs. > I personally like programs that guide me, so I guess it should be in both. Alex