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

Jacob Pan
2019-04-26T16:58:26Z

On Fri, 26 Apr 2019 05:21:15 -0700
Christoph Hellwig <hch@infradead.org> wrote:

> 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!

Make sense, will do that in the next round. Thanks!