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b=bVtQJTaeCkbJtYPLyIXvXF62RPr79fPksVMk14M0zYNX96o6mnHvZFPA0hibhxeHo eEysclkiI4gdSzS6seo2lZ1GnN0cHxD0OLsUdJs+8fu5GWUOojKTc7iVwSQNWxCLkz NeJujBZLVSZmSKqPiolja65PdQe2IWZ9KbYqagJW6TagyYy5DsGI/Dfcn4WqhlCDBK NdACIAkSoyfexQTpPgAhSe9jb0ppgaxsnx0VTxOTB9EkT7naGOqv87ArIiEGUexrqE J+MmMWHcvyWBIENEIWGKWU6/aNbV03JUxv6U5v3cXrfQpAfileqR5zL3eFY2k3lm9C Ap825Q6Z+dW5w== Date: Sun, 21 Jun 2026 13:36:13 +0300 From: Mike Rapoport To: Shyam Saini Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, tgopinath@linux.microsoft.com, bboscaccy@linux.microsoft.com, kees@kernel.org, tony.luck@intel.com, gpiccoli@igalia.com, bp@alien8.de, rdunlap@infradead.org, peterz@infradead.org, feng.tang@linux.alibaba.com, dapeng1.mi@linux.intel.com, elver@google.com, enelsonmoore@gmail.com, kuba@kernel.org, lirongqing@baidu.com, ebiggers@kernel.org Subject: Re: [RFC v2 PATCH] reserve_mem: add support for static memory Message-ID: References: <20260619062331.348789-1-shyamsaini@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260619062331.348789-1-shyamsaini@linux.microsoft.com> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 1FAC4160003 X-Rspam-User: X-Stat-Signature: itfh6crcd91eer6xdxgiu6fojmhwyeur X-HE-Tag: 1782038184-583555 X-HE-Meta: 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 3gWwdB/K +dAAEr9yvtCm2N5+I2i2MlYpp2eEPkaGNuUYoMJsJbcXws3x8L0gW7XWt2hBiBAS707N+pyPloYvSHlzbnFn2yivhf4InCbf9QnvX68AUqZA+TLEuYXzrCTUFuZDqXqOl0b9NsgfIb9polDDw1nBvdI05U/6CEXR7kYSonXz0HZKOhgCqKI87pas9fTZ75M2d+pn5ZqMPHkPt/7rO431CAF7U7U/zlS/S3hcWW51J0vAsgN7CdnCp2OwzQ8dQKbqluOKduxPzK0uLdG4LV99NmNRO0txv3/Rk949dMNQQfA4CIHtU5QNembimQ+Czj7W5lnuuXfyWBlns1EAfhUanKHgfh35lnNYTJmqSDaYOK2NXPC2bFaEN4L3sDbrXp0/pN3ifNgtGlsvoNo8xpwpGCdbLAS+ZX0sbl9bn Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jun 18, 2026 at 11:23:31PM -0700, Shyam Saini wrote: > reserve_mem relies on dynamic memory allocation, this limits the > usecase where memory is required to be preserved across the boots. > Eg: ramoops memory reservation on ACPI platforms > > So add support to pass a pre-determined static address and reserve > memory at a specified location. This enables use case like ramoops > on ACPI platforms to reliably access ramoops region with previous > boot logs. > > Also skip the parsing of when static address is passed. > > Example syntax for static address > reserve_mem=4M@0x1E0000000:oops reserve_mem is best effort by design because such hacks as well as memmap= cannot guarantee this memory is actually free. If you want to preserve ramoops reliably, use KHO with reserve_mem. The first kernel will allocate memory, this memory will be preserved by KHO and could be picked up by the second kernel. > Signed-off-by: Shyam Saini > --- > v1: https://lore.kernel.org/lkml/0eaf3be2-5121-48b7-aeed-196405c0a480@infradead.org/ > v2: Fix code logic and incorporate Randy's suggestion > --- > .../admin-guide/kernel-parameters.txt | 15 ++++++ > mm/memblock.c | 47 +++++++++++++------ > 2 files changed, 47 insertions(+), 15 deletions(-) -- Sincerely yours, Mike.