[PATCH v2 0/2] iommu: Allow passing custom allocators to pgtable drivers

[Jason Gunthorpe]

On Mon, Nov 20, 2023 at 03:38:38PM +0100, Boris Brezillon wrote:

> > At LPC there was quite a lot if interest in improving the io page
> > table stuff to work better. Based on that I'm even more against adding
> > an external allocator at this time. :\
> 
> I'm sure this has been discussed with the IOMMU maintainers, but I'd
> really like to hear it from them if you don't mind. Especially since,
> as I mentioned, the custom allocator idea comes from Robin, not me...

It is a community effort - this is my opinion. We now understand this
io page table area needs a lot of work to meet all the new needs. I'm
against hacking it up like this and making that work harder.

> v1, was a sign this was good to go. If the final call is to reject the
> custom allocator approach, and there's no updates on your generic
> solution in the next couple weeks, I'll probably copy the pgtable code
> in panthor so I can implement my own stuff, and later switch back to
> the generic io-pgtable implementation when things have settled down.

That's horrible, DRM should refuse that too, yet I expect you will
probably end up merging like that.

I would not expect a resolution in a few weeks.

> Nothing against you or your solution (I actually commit to move to the
> new approach when it's ready), but we have different priorities, and I
> can't really delay the driver merging by several months unless there's
> a very good reason to do it.

Welcome to Linux, nothing runs fast :(

Jason