Re: [RFC PATCH 2/2] vfio: Include no-iommu mode

[Gleb Natapov]

On Sun, Oct 11, 2015 at 12:19:54PM +0300, Michael S. Tsirkin wrote:
> > But since you must pass the same value to open(), you already know that
> > you're using noiommu.
> > 
> > >VFIO_IOMMU_MAP_DMA, VFIO_IOMMU_ENABLE and VFIO_IOMMU_DISABLE
> > >will probably also fail ...
> > >
> > 
> > Don't you have to call MAP_DMA to pin the memory?
> 
> Well check it out - the patch in question doesn't implement this ioctl.
> In fact it doesn't implement anything except CHECK_EXTENSION.
> 
> And this makes sense to me: MAP_DMA
> maps a virtual address to io address, and that doesn't
> work for the dummy iommu.
> 
> You can pin memory using many other ways, including
> mlock and hugetlbfs.
> 
mlock() does not pin memory.

--
			Gleb.
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