Re: [Xen-ia64-devel] [RFC] Extended I/O port space support

[Alex Williamson <alex.williamson@xxxxxx>]

On Wed, 2007-06-13 at 07:17 -0400, Jes Sorensen wrote:
> >>>>> "Tristan" == Tristan Gingold <tgingold@xxxxxxx> writes:
> Tristan> This is certainly the right way to do it, but you also have
> Tristan> to specify to the driver domain the io space base (although
> Tristan> it can be remapped).
> 
> First thing that sprung to mind when I read Alex's posting was: does
> anybody actually use IO-ports on ia64 anymore? I thought we managed to
> effectively eliminate them?

   Quite a lot of PCI cards still have I/O port space bars, but
hopefully any "high speed" devices use their MMIO bars exclusively.
This is mainly needed for correctness.  Before this patch, a driver
domain would spew a huge number of errors about trying to map MMIO pages
that Xen wasn't aware.  Once it finally did boot, most drivers seem to
avoid using I/O ports, so the devices work ok.  Then Xen would crash if
I shutdown the domain.  All that is fixed by properly registering and
setting up the I/O port ranges.  And if there is a driver that still
pokes I/O port space bars, at least it will work now.

        Alex

-- 
Alex Williamson                             HP Open Source & Linux Org.


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