Re: [PATCH] firmware: google: coreboot_table: skip no-map CBMEM entries

[Tzung-Bi Shih <tzungbi@kernel.org>]

On Tue, Jul 14, 2026 at 09:19:18AM +0000, Hsin-Te Yuan wrote:
> @@ -147,6 +149,23 @@ static int coreboot_table_populate(struct device *dev, void *ptr, resource_size_
>  
>  		switch (device->entry.tag) {
>  		case LB_TAG_CBMEM_ENTRY:
> +			/*
> +			 * Skip entries that are not exclusively System RAM or
> +			 * Reserved memory.
> +			 * On ARM, no-map reserved regions are not System RAM.
> +			 * On x86, CBMEM often resides in IORES_DESC_RESERVED regions.
> +			 */
> +			if (region_intersects(device->cbmem_entry.address,
> +					      device->cbmem_entry.entry_size,
> +					      IORESOURCE_SYSTEM_RAM,
> +					      IORES_DESC_NONE) != REGION_INTERSECTS &&
> +			    region_intersects(device->cbmem_entry.address,
> +					      device->cbmem_entry.entry_size,
> +					      IORESOURCE_MEM,
> +					      IORES_DESC_RESERVED) != REGION_INTERSECTS) {

Per comments of region_intersects():
    Note that REGION_INTERSECTS is also returned in the case when the
    specified region overlaps RAM and undefined memory holes.

Won't the check falsely be bypassed if the region overlaps SYSTEM_RAM
and `no-map` memory?