Re: [PATCH 0/6] power_of_2 emulation support for NVMe ZNS devices

Keith Busch
2022-03-11T20:51:48Z

On Fri, Mar 11, 2022 at 12:19:38PM -0800, Luis Chamberlain wrote:
> NAND has no PO2 requirement. The emulation effort was only done to help
> add support for !PO2 devices because there is no alternative. If we
> however are ready instead to go down the avenue of removing those
> restrictions well let's go there then instead. If that's not even
> something we are willing to consider I'd really like folks who stand
> behind the PO2 requirement to stick their necks out and clearly say that
> their hw/fw teams are happy to deal with this requirement forever on ZNS.

Regardless of the merits of the current OS requirement, it's a trivial
matter for firmware to round up their reported zone size to the next
power of 2. This does not create a significant burden on their part, as
far as I know.

And po2 does not even seem to be the real problem here. The holes seem
to be what's causing a concern, which you have even without po2 zones.
I'm starting to like the previous idea of creating an unholey
device-mapper for such users...