Re: [RFC 0/7] Proposal to make x86 IOMMU driver support configurable

[Xenia Ragiadakou <burzalodowa@xxxxxxxxx>]

On 12/20/22 12:09, Jan Beulich wrote:
> On 19.12.2022 19:28, Andrew Cooper wrote:
> > IOMMUs are more tricky still.  They are (for most intents and purposes)
> > mandatory on systems with >254 CPUs.  We could in principle start
> > supporting asymmetric IRQ routing on large systems, but Xen doesn't
> > currently and it would be a lot work that's definitely not high on the
> > priority list.  At a minimum, this will need expressing in the Kconfig
> > help text.
> >
> > We need to decide whether it is sensible to allow users to turn off
> > IOMMU support.  It probably is, because you could trivially do this by
> > selecting CONFIG_INTEL only, and booting the result on an AMD system.
> One other thing Andrew and I have been talking about: We probably do
> not want to tie the IOMMU vendor control to CPU vendor one. IOW we'd
> like to be able to e.g. build a hypervisor supporting Intel (only) as
> the CPU vendor, but at the same time having support for an AMD IOMMU.
I totally understand. I am not aiming to tie the AMD/INTEL IOMMU support 
to any particular CPU vendor.
> > For the names, I don't think AMD_IOMMU vs INTEL_VTD is a sensible.
> > Probably wants to be INTEL_IOMMU to match.
> Or simply VTD, covering the case than some other vendor comes up with a
> clone. But of course we have that same issue with "AMD" and Hygon ...
I prefer INTEL_IOMMU over VTD, I think.

> Jan
--
Xenia