# Re: \[PATCH v1 04/11\] mm/memremap: add ZONE\_DEVICE support for compound pages

- From: Dan Williams \<hidden\>
- Date: 2021-06-07 21:57:30 
- List: linux-mm
- Page: https://ratatoskr.run/linux-mm/2021/06/6508668
- Thread: https://ratatoskr.run/linux-mm/2021/03/6507171/t.md

```text
On Mon, Jun 7, 2021 at 2:02 PM Joao Martins [ref] wrote:
[..]
> > But naming aside, I was trying to get at was to avoid a second geometry value validation
> > i.e. to be validated the value and set with a value such as DEVMAP_PTE, DEVMAP_PMD and
> > DEVMAP_PUD.
>
> Sorry my english keeps getting broken, I meant this instead:
>
> But naming aside, what I am trying to get at is to remove the second geometry value
> validation i.e. for @geometry to not be validated a second time to be set to DEVMAP_PTE,
> DEVMAP_PMD or DEVMAP_PUD.
>
> > That to me sounds a little redundant, when the geometry value depends on what
> > align is going to be used from. Here my metnion of @align refers to what's used to create
> > the dax device, not the mmap() align [which can be lower than the device one]. The dax
> > device align is the one used to decide whether to use PTEs, PMDs or PUDs at dax fault handler.
> >
> > So separate concepts, but still its value dependent on one another. At least unless we
> > want to allow geometry values different than those set by --align as Jane suggested.
> >
>
> And I should add:
>
> I can maintain the DEVMAP_* enum values, but then these will need to be changed in tandem
> anytime a new @align value is supported. Or instead we use the name @geometry albeit with
> still as an unsigned long type . Or rather than an unsigned long perhaps making another
> type and its value obtained/changed with getter/setter.

No, feel free to drop the enum and use an explicit "geometry" value
for the vmemmap.

```