RE: [PATCH 1/4] iommu: Add a broken_unmanaged_domain flag in iommu_ops

[Tian, Kevin]

> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Monday, January 30, 2023 9:33 PM
> 
> On Sun, Jan 29, 2023 at 08:11:48AM +0000, Tian, Kevin wrote:
> 
> > " I'd also question sprd-iommu, which hardly has a generally-useful
> > domain size, and has only just recently gained the ability to unmap
> > anything successfully."
> 
> So long as it has a correct kernel API and exposes the right (small)
> aperture then it is OK.
> 
> The device will not be useful for qemu, but it would run some dpdk
> configurations just fine.

I still didn't get the restriction here. Can you elaborate why it works
with dpdk but not qemu?

Can qemu verify this restriction via existing path or need new uAPI
flag to communicate?