Re: [PATCH] acpi/hmat,mm/memtier: always register hmat adist calculation callback

Gregory Price
2024-07-31T14:15:12Z

On Wed, Jul 31, 2024 at 03:20:37PM +0800, Huang, Ying wrote:
> Gregory Price <gourry@gourry.net> writes:
> >
> > In this case, the system is configured explicitly so that kmem does not
> > manage it. In fact, some systems still cannot be managed with
> > EFI_MEMORY_SP due to hpa!=spa issues that the driver cannot manage.
>
> Sorry, I don't understand. IIUC, kmem.c can manage almost any memory
> range via drivers/dax/hmem. Please check
>
> drivers/dax/hmem/device.c
> drivers/dax/hmem/hmem.c
>
> Could you elaborate why kmem.c doesn't work for some memory range?
>

Sorry I misunderstood, I thought you meant the cxl+kmem/hmem subsystem
interaction and handing configuration of the CXL device over to the
kernel.

The boot parameter is not likely to be a solution for us but I will look
at it.

> > But I think a feature that worked in 5.x should work in 6.x, and right
> > now the change in node placement breaks hardware that worked with 5.x
> > which happened to have broken or missing HMAT.