From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792588990; b=aEPNiCnomqIOsvrI4qZnh1e9OYq5Nz7iHHI0RgsFWksZEhFWEXG+wzx6T++qioMHjGYJ 2Imwa9Fzmw54qyf2Mg1Gob6i0+Q5hia6ojbP2tpwTBmo2awmMX4tOie79PtdR3JzjTm8d NYfCEC1LLjMMDvQa1saMO5j3papKjwTPcPcI+xWhQecGqP6HTLaFQ9lmTaeB8I64PbhjK V6wESdR5QJ4GwHZsJKcJ8JegfOj+A8gJKCx7y6XbO2A/CY67zuCq1DZvtdsQ5otumgRTZ xGVG0pASSmQdAbahcHeuBMxhNUV9a4eDxbHbfYabPEjqfJf5y4CbrTtpy5NMdW78I9w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792588990; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=pAAU30bwGvhgKc2fcWmaPUnM+q1nxRImGaxZJ4BonqU=; b=AbE/7N3t1LAA4DgssqqmX8LtJfAqXtmZlQiT45Z889uZtBajXpcFl2KTnUgChc2vTsSm hRACr/Gv8g5G9hFbL11/zZTsRApvK4baxyrvAiwdITG+ctGumv2jn3yGmv2qvoA/J57wP k+jNxokaCBQGyh+aMBFn5fdKa+C72hVZ7ecrvqYD0JEcJ96op+svo+MGUlHlvY0pCKg9h GyqIrGyTiBqlntTbi8bKQqsaIWyEe60CJoG/oyUUpWM98HCUsPzW3kAse+zfzH5wBuv7i DsaYBxyvYVVGntn/Q5L9cpEhGMUFimsofoqZ8Whwg83XvxxFpe+q6DohwvnwHSFKFtA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Mt3hXrxe; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9B16A606A326; Wed, 21 Oct 2026 13:23:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Mt3hXrxe Received: by smtp.kernel.org (Postfix) with ESMTPSA id 039AE1F000C4; Wed, 21 Oct 2026 13:23:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792588990; bh=pAAU30bwGvhgKc2fcWmaPUnM+q1nxRImGaxZJ4BonqU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Mt3hXrxeKJoJfLibADZIcsXR7rI+NO9d5jFB7CsWQi7wKkA7Ivi+NuujoLsu6N0Sj xeAk+R1NrRVYx1sYEncPNYK1tOB4gOmoV/soXvOeMmPj9evSIL4UZE8ME5ru4NQo5h rdmao/ez90tKUwo3/XUgCH2iLLiz95UkX5/e2YrP1miGaCfo8O/R8cfIYLVig3VVnr r1iNDVPFLS7bpM7kU7EAqqH+8hkxOiLRbqqi3tb+hZaOnZwWSQEHk7khqjrR4q7t3A S0lU2etMBYUN25UboD24fjrlEjMmDt+fIwEsaB4T+GmpTzCmxcQVMevggk/I2FaJ6K 4dRr3m+UTBq7A== Date: Wed, 21 Oct 2026 08:23:08 -0500 From: Rob Herring To: Wandun Chen 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 Message-ID: <20261021132308.GB3667411-robh@kernel.org> References: <20261021083011.2170525-1-chenwandun1@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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 > > 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/