Re: [PATCH v2 0/1] arm/arm64: add support for folded p4d page tables

From: Quentin Perret
Date: Fri Jan 24 2020 - 09:02:54 EST


On Friday 24 Jan 2020 at 13:34:35 (+0000), Marc Zyngier wrote:
> I don't disagree at all. To be honest, I've been on the cusp of getting
> rid of it for a while, for multiple reasons:
>
> - It has no users (as you noticed)
> - It is hardly tested (a consequence of the above)
> - It isn't feature complete (no debug, no PMU)
> - It doesn't follow any of the evolution of the architecture (a more
> generic feature of the 32bit port, probably because people run their
> 64bit-capable cores in 64bit mode)
> - It is becoming a mess of empty stubs
>
> The maintenance aspect hasn't been a real problem so far. Even the NV
> support is only about 200 lines of stubs. But what you have in mind is
> going to be much more invasive, and I wouldn't want an unused feature to
> get in the way.
>
> What I may end-up doing is to send a RFC series to remove the 32bit host
> support from the tree during in the 5.6 cycle, targeting 5.7. If someone
> shouts loudly during that time frame, we keep it and you'll have to work
> around it. If nobody cares, then dropping it is the right thing to do.
>
> Would that be OK with you?

Absolutely. And yes, if there are users of the 32 bits port, it'll be on
us to work around in a clean way, but I think this is perfectly fair.
I'll be happy to try and test your RFC series when it goes on the list
if that can help.

Thanks!
Quentin