Re: [PATCH 4/5] resource: Report parent to walk_iomem_res_desc() callback

From: Dan Williams
Date: Tue Mar 17 2020 - 18:05:01 EST


On Thu, Mar 5, 2020 at 6:42 AM Tom Lendacky <thomas.lendacky@xxxxxxx> wrote:
>
> On 3/2/20 4:20 PM, Dan Williams wrote:
> > In support of detecting whether a resource might have been been claimed,
> > report the parent to the walk_iomem_res_desc() callback. For example,
> > the ACPI HMAT parser publishes "hmem" platform devices per target range.
> > However, if the HMAT is disabled / missing a fallback driver can attach
> > devices to the raw memory ranges as a fallback if it sees unclaimed /
> > orphan "Soft Reserved" resources in the resource tree.
> >
> > Otherwise, find_next_iomem_res() returns a resource with garbage data
> > from the stack allocation in __walk_iomem_res_desc() for the res->parent
> > field.
>
> Just wondering if we shouldn't just copy the complete resource struct and
> just override the start and end values? That way, if some code in the
> future wants to look at sibling or child values, another change isn't needed.
>
> Just a thought.

Thanks for taking a look. I think it's ok to come update this again if
that need arises.