Re: [PATCH v2 06/19] drivers core: Add I/O ASID allocator

Christoph Hellwig
2019-04-26T12:23:24Z

On Fri, Apr 26, 2019 at 12:47:43PM +0100, Jean-Philippe Brucker wrote:
> >> On Tue, Apr 23, 2019 at 04:31:06PM -0700, Jacob Pan wrote:
> >>> The allocator doesn't really belong in drivers/iommu because some
> >>> drivers would like to allocate PASIDs for devices that aren't
> >>> managed by an IOMMU, using the same ID space as IOMMU. It doesn't
> >>> really belong in drivers/pci either since platform device also
> >>> support PASID. Add the allocator in drivers/base.
> >>
> >> I'd still add it to drivers/iommu, just selectable separately from the
> >> core iommu code..
> > Perhaps I misunderstood. If a driver wants to use IOASIDs w/o iommu
> > subsystem even turned on, how could selecting from the core iommu code
> > help? Could you elaborate on "selectable"?
>
> How about doing the same as CONFIG_IOMMU_IOVA? The code is in
> drivers/iommu but can be selected by non-IOMMU_API users, independently
> of CONFIG_IOMMU_SUPPORT. It's true that this allocator will mostly be
> used by IOMMU drivers.

That is exactly what I meant!