Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753497AbdDKVMR (ORCPT ); Tue, 11 Apr 2017 17:12:17 -0400 Received: from mail.kernel.org ([198.145.29.136]:41616 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752918AbdDKVMQ (ORCPT ); Tue, 11 Apr 2017 17:12:16 -0400 Date: Tue, 11 Apr 2017 16:12:11 -0500 From: Bjorn Helgaas To: bodong@mellanox.com Cc: bhelgaas@google.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, saeedm@mellanox.com, Eli Cohen Subject: Re: [v2] PCI: Add an option to control probing of VFs before enabling SR-IOV Message-ID: <20170411211211.GB14778@bhelgaas-glaptop.roam.corp.google.com> References: <1490198038-20465-1-git-send-email-bodong@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1490198038-20465-1-git-send-email-bodong@mellanox.com> 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 Content-Length: 1469 Lines: 35 Hi Bodong, On Wed, Mar 22, 2017 at 05:53:58PM +0200, bodong@mellanox.com wrote: > From: Bodong Wang > > Sometimes it is not desirable to probe the virtual functions after > SRIOV is enabled. This can save host side resource usage by VF > instances which would be eventually probed to VMs. > > Add a new PCI sysfs interface "sriov_probe_vfs" to control that > from the PF, all current callers still retain the same functionality. > To modify it, echo 0/n/N (disable probe) or 1/y/Y (enable probe) to > > /sys/bus/pci/devices//sriov_probe_vfs Is this basically the same functionality as /sys/bus/pci/drivers_autoprobe, but limited to a specific PF? I.e., could we accomplish the same thing with the following? # echo 0 > /sys/bus/pci/devices/DDDD:BB:dd.f/sriov_numvfs # echo 0 > /sys/bus/pci/drivers_autoprobe # echo 2 > /sys/bus/pci/devices/DDDD:BB:dd.f/sriov_numvfs # echo 1 > /sys/bus/pci/drivers_autoprobe If not, can you contrast the above with drivers_autoprobe? If we need both, should they be named more similarly? > Note that, the choice must be made before enabling VFs. The change > will not take effect if VFs are already enabled. Simply, one can set > sriov_numvfs to 0, choose whether to probe or not, and then resume > sriov_numvfs. > > Signed-off-by: Bodong Wang > Signed-off-by: Eli Cohen > Reviewed-by: Gavin Shan