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Fri, 12 Feb 2021 01:18:02 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lAN5r-00066n-0n for linux-arm-kernel@lists.infradead.org; Fri, 12 Feb 2021 01:18:00 +0000 Received: from [192.168.0.104] (c-73-42-176-67.hsd1.wa.comcast.net [73.42.176.67]) by linux.microsoft.com (Postfix) with ESMTPSA id 3434B20B6C40; Thu, 11 Feb 2021 17:17:57 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 3434B20B6C40 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1613092677; bh=Y7BtTH5ulPnacnf3FX5f0RFcRSYsD0USlFVkCyasTd4=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=gyo459klbjM84xwkX6PXkazK+7OzLyws3VPz679/pgnVlag/yYxfVMm7nXbGMrkcm tMcaGkes9he/hxnfLrRRLCNmuf6kZxit5kxbALc4vmgd+a1J78MYVjD93gERNjxLcM U979bY8a948Kz/YGiY2ldd16eUNbb2nnfsD1Ybms= Subject: Re: [PATCH v17 02/10] of: Add a common kexec FDT setup function To: Thiago Jung Bauermann References: <20210209182200.30606-1-nramas@linux.microsoft.com> <20210209182200.30606-3-nramas@linux.microsoft.com> <87k0reozwh.fsf@manicouagan.localdomain> From: Lakshmi Ramasubramanian Message-ID: <8a3aa3d2-2eba-549a-9970-a2b0fe3586c9@linux.microsoft.com> Date: Thu, 11 Feb 2021 17:17:56 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <87k0reozwh.fsf@manicouagan.localdomain> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210211_201759_207396_61F50C50 X-CRM114-Status: GOOD ( 19.01 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, benh@kernel.crashing.org, tao.li@vivo.com, zohar@linux.ibm.com, paulus@samba.org, vincenzo.frascino@arm.com, frowand.list@gmail.com, sashal@kernel.org, robh@kernel.org, mpe@ellerman.id.au, masahiroy@kernel.org, jmorris@namei.org, takahiro.akashi@linaro.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, serge@hallyn.com, devicetree@vger.kernel.org, pasha.tatashin@soleen.com, will@kernel.org, prsriva@linux.microsoft.com, hsinyi@chromium.org, allison@lohutok.net, christophe.leroy@c-s.fr, mbrugger@suse.com, balajib@linux.microsoft.com, dmitry.kasatkin@gmail.com, linux-kernel@vger.kernel.org, james.morse@arm.com, gregkh@linuxfoundation.org, joe@perches.com, linux-integrity@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2/11/21 5:09 PM, Thiago Jung Bauermann wrote: > > There's actually a complication that I just noticed and needs to be > addressed. More below. > <...> >> + >> +/* >> + * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree >> + * >> + * @image: kexec image being loaded. >> + * @initrd_load_addr: Address where the next initrd will be loaded. >> + * @initrd_len: Size of the next initrd, or 0 if there will be none. >> + * @cmdline: Command line for the next kernel, or NULL if there will >> + * be none. >> + * >> + * Return: fdt on success, or NULL errno on error. >> + */ >> +void *of_kexec_alloc_and_setup_fdt(const struct kimage *image, >> + unsigned long initrd_load_addr, >> + unsigned long initrd_len, >> + const char *cmdline) >> +{ >> + void *fdt; >> + int ret, chosen_node; >> + const void *prop; >> + unsigned long fdt_size; >> + >> + fdt_size = fdt_totalsize(initial_boot_params) + >> + (cmdline ? strlen(cmdline) : 0) + >> + FDT_EXTRA_SPACE; > > Just adding 4 KB to initial_boot_params won't be enough for crash > kernels on ppc64. The current powerpc code doubles the size of > initial_boot_params (which is normally larger than 4 KB) and even that > isn't enough. A patch was added to powerpc/next today which uses a more > precise (but arch-specific) formula: > > https://lore.kernel.org/linuxppc-dev/161243826811.119001.14083048209224609814.stgit@hbathini/ > > So I believe we need a hook here where architectures can provide their > own specific calculation for the size of the fdt. Perhaps a weakly > defined function providing a default implementation which an > arch-specific file can override (a la arch_kexec_kernel_image_load())? > > Then the powerpc specific hook would be the kexec_fdt_totalsize_ppc64() > function from the patch I linked above. > Do you think it'd better to add "fdt_size" parameter to of_kexec_alloc_and_setup_fdt() so that the caller can provide the desired FDT buffer size? thanks, -lakshmi _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel