From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Date: Sun, 18 Jul 2021 12:31:21 +0300 From: Mike Rapoport Subject: Re: [PATCH v4 02/10] memblock: Add variables for usable memory limitation Message-ID: References: <04c4d231fb03a3810d72a45c8a5bc2272c5975f3.1626266516.git.geert+renesas@glider.be> <20210714135101.GB2441138@robh.at.kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210714135101.GB2441138@robh.at.kernel.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Rob Herring Cc: Geert Uytterhoeven , Russell King , Nicolas Pitre , Ard Biesheuvel , Linus Walleij , Catalin Marinas , Will Deacon , Nick Kossifidis , Paul Walmsley , Palmer Dabbelt , Albert Ou , Frank Rowand , Dave Young , Baoquan He , Vivek Goyal , Andrew Morton , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, kexec@lists.infradead.org, linux-mm@kvack.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org Hi, On Wed, Jul 14, 2021 at 07:51:01AM -0600, Rob Herring wrote: > On Wed, Jul 14, 2021 at 02:50:12PM +0200, Geert Uytterhoeven wrote: > > Add two global variables (cap_mem_addr and cap_mem_size) for storing a > > base address and size, describing a limited region in which memory may > > be considered available for use by the kernel. If enabled, memory > > outside of this range is not available for use. > > > > These variables can by filled by firmware-specific code, and used in > > calls to memblock_cap_memory_range() by architecture-specific code. > > An example user is the parser of the "linux,usable-memory-range" > > property in the DT "/chosen" node. > > > > Signed-off-by: Geert Uytterhoeven > > --- > > This is similar to how the initial ramdisk (phys_initrd_{start,size}) > > and ELF core headers (elfcorehdr_{addr,size})) are handled. > > > > Does there exist a suitable place in the common memblock code to call > > "memblock_cap_memory_range(cap_mem_addr, cap_mem_size)", or does this > > have to be done in architecture-specific code? > > Can't you just call it from early_init_dt_scan_usablemem? If the > property is present, you want to call it. If the property is not > present, nothing happens. For memblock_cap_memory_range() to work properly it should be called after memory is detected and added to memblock with memblock_add[_node]() I'm not huge fan of adding more globals to memblock so if such ordering can be implemented on the DT side it would be great. I don't see a way to actually enforce this ordering, so maybe we'd want to add warning in memblock_cap_memory_range() if memblock.memory is empty. > Rob -- Sincerely yours, Mike. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec