Re: [dpdk-dev] [PATCH 0/2] uio_msi: device driver

[Stephen Hemminger]

On Thu, 1 Oct 2015 12:48:36 -0700
Alexander Duyck <alexander.duyck@xxxxxxxxx> wrote:

> On 10/01/2015 07:57 AM, Stephen Hemminger wrote:
> > On Thu, 1 Oct 2015 13:59:02 +0300
> > Avi Kivity <avi@xxxxxxxxxxxx> wrote:
> >
> >> On 10/01/2015 01:28 AM, Stephen Hemminger wrote:
> >>> This is a new UIO device driver to allow supporting MSI-X and MSI devices
> >>> in userspace.  It has been used in environments like VMware and older versions
> >>> of QEMU/KVM where no IOMMU support is available.
> >> Why not add msi/msix support to uio_pci_generic?
> > That is possible but that would meet ABI and other resistance from the author.
> > Also, uio_pci_generic makes it harder to find resources since it doesn't fully
> > utilize UIO infrastructure.
> 
> I'd say you are better off actually taking this in the other direction.  
> From what I have seen it seems like this driver is meant to deal with 
> mapping VFs contained inside of guests.  If you are going to fork off 
> and create a UIO driver for mapping VFs why not just make it specialize 
> in that.  You could probably simplify the code by dropping support for 
> legacy interrupts and IO regions since all that is already covered by 
> uio_pci_generic anyway if I am not mistaken.
> 
> You could then look at naming it something like uio_vf since the uio_msi 
> is a bit of a misnomer since it is MSI-X it supports, not MSI interrupts.

The support needs to cover:
  - VF in guest
  - VNIC in guest (vmxnet3)
it isn't just about VF's
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