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

Alexander Duyck
2015-10-01T19:48:40Z

On 10/01/2015 07:57 AM, Stephen Hemminger wrote:
> On Thu, 1 Oct 2015 13:59:02 +0300
> Avi Kivity <avi@scylladb.com> 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.

- Alex