Re: [PATCH v2 1/4] kernel/resource: Introduce managed SOFT RESERVED resources

David Hildenbrand
2025-01-21T08:19:30Z

On 16.01.25 18:42, Nathan Fontenot wrote:

Hi,

> Introduce the ability to manage SOFT RESERVED kernel resources prior to
> these resources being placed in the iomem resource tree. This provides
> the ability for drivers to update SOFT RESERVED resources that intersect
> with their memory resources.
>
> During boot, any resources marked as IORES_DESC_SOFT_RESERVED are placed
> on the soft reserve resource tree. Once boot completes all resources
> are placed on the iomem resource tree. This behavior is gated by a new
> kernel option CONFIG_SOFT_RESERVED_MANAGED.
>

I'm missing a bit of context here.

Why can't we flag these regions in the existing iomem tree, where they
can be fixed up (even after boot?)?

Especially, what about deferred driver loading after boot? Why is that
not a concern or why can we reliably handle everything "during boot" ?

> As part of this update two new interfaces are added for management of
> the SOFT RESERVED resources. The release_srmem_region_adjustable()
> routine allows for removing pieces of SOFT RESERVED resources. The
> the merge_srmem_resources() allows drivers to merge any remaining SOFT
> RESERVED resources into the iomem resource tree once updatea are complete.
>
> Signed-off-by: Nathan Fontenot <nathan.fontenot@amd.com>

--
Cheers,

David / dhildenb