[PATCH v9 0/8] kdump: reduce vmcore size and capture time

[Rob Herring]

On Wed, Oct 21, 2026 at 04:30:03PM +0800, Wandun Chen wrote:
> From: Wandun Chen <chenwandun at lixiang.com>
> 
> On SoCs that carve out large firmware-owned reserved memory (GPU,
> camera ISP, ...), kdump currently dumps those carveouts as part of
> system RAM even though their contents are firmware state that is not
> useful for kernel crash analysis.
> 
> ACPI systems already filter reserved memory out of the vmcore through
> their existing path: firmware reports those carveouts as unusable in
> the EFI memory map, they get MEMBLOCK_NOMAP set in memblock.memory
> (is_usable_memory(), efi-init.c), and the ELF header builder has
> always skipped nomap regions; only DT-based systems currently fail
> to filter these regions, which is what this series addresses.
> 
> This series introduces a MEMBLOCK_NODUMP flag (suggested by Rob) in
> memblock to filter reserved memory on DT-based architectures. A new
> flag is needed because MEMBLOCK_NOMAP can only express regions without
> a linear mapping, while MEMBLOCK_NODUMP can filter regions that are
> linearly mapped. Reserved regions are marked MEMBLOCK_NODUMP by default
> so kdump omits them; reusable CMA regions are different because their
> pages are handed back to the buddy allocator and may carry crash-relevant
> data.

There is little point in continuing to send new versions until Mike 
agrees with MEMBLOCK_NODUMP being added. You didn't answer him on v7.

Also, I intend to apply this[1] before any further reserved memory 
changes which will greatly simplify the code.

Rob

[1] https://lore.kernel.org/all/20261015082315.56876-1-m.szyprowski@samsung.com/