From: Eli Cohen <eli@mellanox.com>
To: Alex Williamson <alex.williamson@redhat.com>,
        Gavin Shan <gwshan@linux.vnet.ibm.com>
CC: Bodong Wang <bodong@mellanox.com>,
        "bhelgaas@google.com" <bhelgaas@google.com>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Saeed Mahameed <saeedm@mellanox.com>
Subject: RE: [PATCH] pci/sriov: Add an option to probe VFs or not before
 enabling SR-IOV
Thread-Topic: [PATCH] pci/sriov: Add an option to probe VFs or not before
 enabling SR-IOV
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Date: Tue, 21 Mar 2017 14:34:46 +0000
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> If we want to talk about the ABI, I would suggest drawing from existing ABIs.  We already have
> drivers_autoprobe as part of the standard sysfs ABI, so if we want a binary switch, then 
>sriov_drivers_autoprobe might be a logical choice.  If you're concerned about this mythical overhead of > binding to one driver then another, then why not draw from the driver_override interface to allow the 
> user to specify the driver to bind to, perhaps sriov_driver_override.  Then if the user wants to bind all 
> the devices to vfio-pci, they can do so easily.  I still fail to see that probing some fixed number of the VFs 
> and leaving the rest unprobed has any practical value and I imagine bugs coming in because users are 
> confused why some of their VFs behave differently than others.  Thanks,

I agree with Alex - the interface should better be binary - either probe VFs or not. The rest can be done with binding/unbinding VFs as necessary. The main goal is to refrain from automatically initializing virtual functions at the hypervisor if they were initially instantiated to assign then to guests.