From: Rob Herring <robh@kernel.org>
To: Wandun Chen <chenwandun1@gmail.com>
Cc: baoquan.he@linux.dev, rppt@kernel.org, m.szyprowski@samsung.com,
catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com,
chenhuacai@kernel.org, kernel@xen0n.name, pjw@kernel.org,
palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr,
tglx@kernel.org, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
saravanak@kernel.org, akpm@linux-foundation.org,
pasha.tatashin@soleen.com, pratyush@kernel.org,
ruirui.yang@linux.dev, robin.murphy@arm.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, loongarch@lists.linux.dev,
linux-riscv@lists.infradead.org, devicetree@vger.kernel.org,
kexec@lists.infradead.org, linux-mm@kvack.org,
iommu@lists.linux.dev
Subject: Re: [PATCH v9 0/8] kdump: reduce vmcore size and capture time
Date: Wed, 21 Oct 2026 08:23:08 -0500 [thread overview]
Message-ID: <20261021132308.GB3667411-robh@kernel.org> (raw)
In-Reply-To: <20261021083011.2170525-1-chenwandun1@gmail.com>
On Wed, Oct 21, 2026 at 04:30:03PM +0800, Wandun Chen wrote:
> From: Wandun Chen <chenwandun@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/
prev parent reply other threads:[~2026-10-21 13:23 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-21 8:30 Wandun Chen
2026-10-21 8:30 ` [PATCH v9 1/8] riscv: build crash_mem ranges from memblock instead of resource tree Wandun Chen
2026-10-21 9:05 ` Jinjie Ruan
2026-10-21 9:05 ` Jinjie Ruan
2026-10-21 8:30 ` [PATCH v9 2/8] crash_core: fold duplicated memblock arch hooks into the weak default Wandun Chen
2026-10-21 8:30 ` [PATCH v9 3/8] crash_core: serialize crash header preparation against hotplug Wandun Chen
2026-10-21 9:13 ` Jinjie Ruan
2026-10-21 9:48 ` Wandun
2026-10-21 8:30 ` [PATCH v9 4/8] crash_core: replace for_each_mem_range() with for_each_mem_region() Wandun Chen
2026-10-21 8:30 ` [PATCH v9 5/8] memblock: introduce MEMBLOCK_NODUMP flag Wandun Chen
2026-10-21 8:30 ` [PATCH v9 6/8] of: reserved_mem: add dumpable flag to opt-in vmcore Wandun Chen
2026-10-21 8:30 ` [PATCH v9 7/8] of: reserved_mem: mark /reserved-memory entries with MEMBLOCK_NODUMP Wandun Chen
2026-10-21 8:30 ` [PATCH v9 8/8] crash_core: skip MEMBLOCK_NODUMP regions when building vmcore ELF header Wandun Chen
2026-10-21 13:23 ` Rob Herring [this message]
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