Re: [PATCH v2 2/2] x86/of: add support for reserved memory defined by DT

[Rob Herring <robh@kernel.org>]

On Fri, Apr 18, 2025 at 12:47:18PM +0000, Grzegorz Jaszczyk wrote:
> From: Grzegorz Jaszczyk <jaszczyk@google.com>
> 
> The DT reserved-memory nodes can be present in DT as described in
> Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml.
> Similar to other architecture, which supports DT, there is a need to
> create reserved memory regions for such nodes.
> 
> Additionally, the x86 architecture builds its memory map based on E820
> description passed by bootloader and not on DT. Since x86 already has
> some DT support and allows booting with both ACPI and DT at the same
> time, let's register an arch specific hook which will validate if a
> reserved-memory region passed by DT is valid (covered by E820 reserved
> region entry).
> 
> Without this check, the reserved memory from DT could be successfully
> registered, even though such a region could conflict with e820
> description e.g. it could be described as E820_RAM and could be already
> used at early x86 boot stage for memblock initialization (which happens
> before DT parsing).

Sorry, I don't get how it conflicts. Wouldn't the E820_RAM be registered 
with memblock and memblock then handles the conflict (or should).

Rob