Re: [PATCH v3 00/10] EFI Specific Purpose Memory Support

From: Dave Hansen
Date: Fri Jun 07 2019 - 16:02:07 EST

On 6/7/19 12:27 PM, Dan Williams wrote:
> In support of optionally allowing either application-exclusive and
> core-kernel-mm managed access to differentiated memory, claim
> EFI_MEMORY_SP ranges for exposure as device-dax instances by default.
> Such instances can be directly owned / mapped by a
> platform-topology-aware application. Alternatively, with the new kmem
> facility [4], the administrator has the option to instead designate that
> those memory ranges be hot-added to the core-kernel-mm as a unique
> memory numa-node. In short, allow for the decision about what software
> agent manages specific-purpose memory to be made at runtime.

It's probably worth noting that the reason the memory lands into the
state of being controlled by device-dax by default is that device-dax is
nice. It's actually willing and able to give up ownership of the memory
when we ask. If we added to the core-mm, we'd almost certainly not be
able to get it back reliably.

Anyway, thanks for doing these, and I really hope that the world's
BIOSes actually use this flag. For the series:

Reviewed-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>