Re: [PATCH 4/4] powerpc/pseries/iommu: Remove default DMA window before creating DDW

[Leonardo Bras]

On Tue, 2020-06-23 at 12:35 +1000, Alexey Kardashevskiy wrote:
> > I am not sure if this is true in general, but in this device (SR-IOV
> > VF) I am testing it will return 0 windows if the default DMA window is
> > not deleted, and 1 after it's deleted.
> 
> Since pHyp can only create windows in "64bit space", now (I did not know
> until a few month back) I expect that thing to return "1" always no
> matter what happened to the default window. And removing the default
> window will only affect the maximum number of TCEs but not the number of
> possible windows.

Humm, something gone wrong then.

This patchset was developed mostly because on testing, DDW would never
be created because windows_available would always be 0.

I will take a deeper look in that.

Best regards,
Leonardo