From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH RFC] seabios: add OSHP method stub Date: Tue, 14 Feb 2012 15:37:28 +0200 Message-ID: <20120214133727.GA23647@redhat.com> References: <20120214004837.GA14752@morn.localdomain> <20120214010913.GA5192@redhat.com> <201202141249.09301.paul@codesourcery.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Kevin Wolf , kvm@vger.kernel.org, seabios@seabios.org, qemu-devel@nongnu.org, Isaku Yamahata , Kevin O'Connor , Avi Kivity To: Paul Brook Return-path: Content-Disposition: inline In-Reply-To: <201202141249.09301.paul@codesourcery.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org On Tue, Feb 14, 2012 at 12:49:08PM +0000, Paul Brook wrote: > > > In a nutshell, I don't know what a SHPC is (nor OSHP), so I'm looking > > > for an additional Ack. > > > > No problem, I'll get an Ack :) > > Meanwhile - here's a summary, as far as I understand it. > > > > Originally PCI SIG only defined the electrical > > and mechanical requirements from hotplug, no standard > > software interface. So it needed ACPI to drive device-specific registers > > to actually do hotplug. > > At some point PCISIG defined standard interfaces > > for PCI hotplug. There are two of them: standard > > hot plug controller (SHPC) for PCI and PCIE hotplug > > for Express. > > > > Now an OS can have a standard driver and use it > > to activate hotplug functionality. This is OS hotplug (OSHP). > > So presumably this will work on targets that don't have ACPI? > Assuming a competent guest OS of course. Have you tested this? > > Paul This being the qemu side of things? I run Linux and verified that it calls OSHP and afterwards, runs the native driver and handles hotplug/unplug without invoking ACPI at all. It seems that at least the SHPC driver in linux doesn't work if you don't have an acpi table with the OSHP method - not many people run with acpi=off nowdays, so it's probably just a bug. I'll check how hard it is to fix this. -- MST