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Date: Tue, 28 Apr 2015 09:33:24 -0700
From: Stephen Hemminger <stephen@networkplumber.org>
To: "Qiu, Michael" <michael.qiu@intel.com>
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Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] What to do about UIO breakage in 2.0
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On Tue, 28 Apr 2015 08:07:18 +0000
"Qiu, Michael" <michael.qiu@intel.com> wrote:

> On 4/28/2015 6:06 AM, Stephen Hemminger wrote:
> > I raised the issue, but people seem to be ignoring that fact that igb_uio
> > was broken by the introduction of UIO PCI generic in 2.0.
> 
> What do you mean about igb_uio broken?
> 
> Thanks,
> Michael
> >
> > There are three options:
> >  1. Remove IGB_UIO only use UIO PCI generic.
> >     Downside there is no MSI-X support for UIO PCI generic.
> >  2. Revert UIO PCI generic support
> >  3. Replace both of the above with something better.
> >
> > I am working on #3 but it will not be ready for 2.0.1 and there
> > is no solution for users of 2.0 and any future stable code.
> >
> 

If you use link state interrupt, then the base code in eal_interrupts
is now broken when using igb_uio. The code was changed to work with
uio_pci_generic. The new code does read/write of PCI INTX config and
will not work when using igb_uio which uses MSI-X.

Some possible solutions are:
 1. Remove igb_uio completely 
 2. Revert/remove uio_pci_generic and use old read/write to enable irq
 3. Make code look at driver type (sending patches for that now).
 4. Implement a better UIO method for MSI-X which is what I will submit
    when Rx IRQ support is ready.