On Wed, Dec 02, 2015 at 05:19:18PM +0100, Thomas Monjalon wrote: > Hi, > > 2015-12-02 08:28, Alex Williamson: > > On Mon, 2015-11-16 at 19:12 +0200, Avi Kivity wrote: > > > On 11/16/2015 07:06 PM, Alex Williamson wrote: > > > > FYI, this is now in v4.4-rc1 (the slightly modified v2 version). I want > > > > to give fair warning though that while we seem to agree on this idea, it > > > > hasn't been proven with a userspace driver port. I've opted to include > > > > it in this merge window rather than delaying it until v4.5, but I really > > > > need to see a user for this before the end of the v4.4 cycle or I think > > > > we'll need to revert and revisit for v4.5 anyway. I don't really have > > > > any interest in adding and maintaining code that has no users. Please > > > > keep me informed of progress with a dpdk port. Thanks, > > > > > > Thanks Alex. Copying the dpdk mailing list, where the users live. > > > > > > dpdk-ers: vfio-noiommu is a replacement for uio_pci_generic and > > > uio_igb. It supports MSI-X and so can be used on SR/IOV VF devices. > > > The intent is that you can use dpdk without an external module, using > > > vfio, whether you are on bare metal with an iommu, bare metal without an > > > iommu, or virtualized. However, dpdk needs modification to support this. > > > > Still no users for this that I'm aware of. I'm going to revert this in > > rc5 unless something changes. Thanks, > > Removing needs for out-of-tree modules is a really nice achievement. > Yes, we (in the DPDK project) should check how to use this no-iommu VFIO > and to replace igb_uio. > > I'm sorry we failed to catch your email and follow up. > Is it really too late? What is the risk of keeping it in Linux 4.4? > Advertising a new feature and removing it would be frustrating. > > Have you tried this VFIO mode with DPDK? > How complex would be the patch to support it? > > Thanks
These things need to be developed together, one can't be sure it meets userspace needs if no one tried. And then where would we be? Supporting a broken interface forever. If someone writes the userspace code, then this feature can come back for 4.5. -- MST
