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Thu, 07 May 2026 02:42:00 -0700 (PDT) Message-ID: Date: Thu, 7 May 2026 17:41:49 +0800 Precedence: bulk X-Mailing-List: loongarch@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 05/11] of: reserved_mem: add linux,no-dump property support for reserved memory regions To: Rob Herring Cc: kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, akpm@linux-foundation.org, bhe@redhat.com, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, ruirui.yang@linux.dev, corbet@lwn.net, skhan@linuxfoundation.org, catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org, kernel@xen0n.name, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, saravanak@kernel.org, chenwandun@lixiang.com, zhaomeijing@lixiang.com, everyzhao@126.com References: <20260429065831.1510858-1-chenwandun@lixiang.com> <20260429065831.1510858-6-chenwandun@lixiang.com> <20260506144542.GA2072596-robh@kernel.org> Content-Language: en-US From: Wandun In-Reply-To: <20260506144542.GA2072596-robh@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 5/6/26 22:45, Rob Herring wrote: > On Wed, Apr 29, 2026 at 02:58:25PM +0800, Chen Wandun wrote: >> Add a 'no_dump' field to struct reserved_mem and parse the >> 'linux,no-dump' device tree property during reserved memory node >> initialization. This property allows device tree authors to mark >> specific reserved memory regions that should be excluded from kdump >> vmcore dumps. >> >> Reserved memory regions used by device firmware (e.g., GPU, DSP, modem) >> typically contain data that is not useful for kernel crash analysis and >> can significantly increase vmcore size. The 'linux,no-dump' property >> provides a declarative way to indicate these regions should be filtered >> out when constructing the elfcorehdr for kdump. >> >> The property is named with a 'linux,' prefix because kdump/vmcore is >> Linux-specific and the property is an OS hint rather than a hardware >> description, matching existing properties such as 'linux,cma-default' >> and 'linux,usable-memory-range'. >> >> The 'linux,no-dump' property is only effective when the region: >> - Does not have 'no-map': these regions are already excluded from >> vmcore since they are removed from the linear mapping (MEMBLOCK_NOMAP). >> - Does not have 'reusable': CMA reusable regions are actively used by >> the kernel for movable page allocations, and their contents are >> valuable for crash analysis. >> >> The no-dump status is also printed in the boot log alongside the >> existing nomap and reusable flags for diagnostic purposes. > I think this property is the wrong way around and probably not needed. > The default should be exclude the regions, but if Linux is using the > regions (like CMA) then it can decide on its own to include them. > > With the restructuring that went into 7.1, it should be possible for the > CMA code (and code for any other regions) to set some flag for the > region. Agree that the property direction is wrong. Rework in v2:   - Default: exclude reserved regions from vmcore   - CMA (reusable) setup path marks regions as kernel-managed general memory → include   - No DT binding needed; linux,no-dump proposal withdrawn Thanks. > > Rob