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Fri, 12 Feb 2021 01:39:21 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E1331112063; Fri, 12 Feb 2021 01:39:20 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B0F12112064; Fri, 12 Feb 2021 01:39:13 +0000 (GMT) Received: from manicouagan.localdomain (unknown [9.85.204.73]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTPS; Fri, 12 Feb 2021 01:39:13 +0000 (GMT) References: <20210209182200.30606-1-nramas@linux.microsoft.com> <20210209182200.30606-3-nramas@linux.microsoft.com> <87k0reozwh.fsf@manicouagan.localdomain> <8a3aa3d2-2eba-549a-9970-a2b0fe3586c9@linux.microsoft.com> User-agent: mu4e 1.4.10; emacs 27.1 From: Thiago Jung Bauermann To: Lakshmi Ramasubramanian Subject: Re: [PATCH v17 02/10] of: Add a common kexec FDT setup function In-reply-to: <8a3aa3d2-2eba-549a-9970-a2b0fe3586c9@linux.microsoft.com> Date: Thu, 11 Feb 2021 22:39:11 -0300 Message-ID: <87h7mioyio.fsf@manicouagan.localdomain> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369, 18.0.737 definitions=2021-02-11_07:2021-02-11, 2021-02-11 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 priorityscore=1501 suspectscore=0 adultscore=0 mlxlogscore=999 impostorscore=0 spamscore=0 mlxscore=0 clxscore=1015 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102120002 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210211_205730_324281_18539C2B X-CRM114-Status: GOOD ( 20.59 ) 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Lakshmi Ramasubramanian writes: > 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? Yes, that is actually simpler and better than my idea. :-) -- Thiago Jung Bauermann IBM Linux Technology Center _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel