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Thu, 20 Feb 2025 16:43:49 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A8F0820043; Thu, 20 Feb 2025 16:43:49 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4888520040; Thu, 20 Feb 2025 16:43:49 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTPS; Thu, 20 Feb 2025 16:43:49 +0000 (GMT) Date: Thu, 20 Feb 2025 17:43:48 +0100 From: Alexander Gordeev To: Dave Young Cc: Alexander Graf , Mike Rapoport , linux-kernel@vger.kernel.org, Andrew Morton , Andy Lutomirski , Anthony Yznaga , Arnd Bergmann , Ashish Kalra , Benjamin Herrenschmidt , Borislav Petkov , Catalin Marinas , Dave Hansen , David Woodhouse , Eric Biederman , Ingo Molnar , James Gowans , Jonathan Corbet , Krzysztof Kozlowski , Mark Rutland , Paolo Bonzini , Pasha Tatashin , "H. Peter Anvin" , Peter Zijlstra , Pratyush Yadav , Rob Herring , Rob Herring , Saravana Kannan , Stanislav Kinsburskii , Steven Rostedt , Thomas Gleixner , Tom Lendacky , Usama Arif , Will Deacon , devicetree@vger.kernel.org, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, Philipp Rudo , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , linux-s390@vger.kernel.org Subject: Re: [PATCH v4 00/14] kexec: introduce Kexec HandOver (KHO) Message-ID: References: <20250206132754.2596694-1-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 02CmlzRAvH6gUhNjDul_d5grRXN4j5Cf X-Proofpoint-GUID: vqtrf0KyRdj5sNl93G5J7u-LcnzQFqNz X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-02-20_07,2025-02-20_02,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 suspectscore=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 mlxlogscore=660 bulkscore=0 phishscore=0 malwarescore=0 mlxscore=0 adultscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502100000 definitions=main-2502200116 X-Rspamd-Queue-Id: 91B66C0020 X-Stat-Signature: 7nspki3m4etnjtmm3ontrry8a3tmc1za X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1740069867-777245 X-HE-Meta: U2FsdGVkX18Qgz7a7aHBn/wFFUpBxQj9+eLRme0sKpmfIZ2tocKZYNojXinqSGx/Q/oUcbr7UOpCkPQsxMq6dp1VDjSNmOxqWPMJlL59DJinv5fgv4bpUZYi3M5fw5xTJIc7Io4etIsiGv4LJuGw22D3Cshh6sE5qVl8zPa6cuSTyIHXycvxs8/tfUY7ANstVPQDGemOzFXY3YAsw/HMcDLGzgFIvMAqePfOHZYCLdzEiLDGnxn7TdaK1Qqa6Kxl6rnT0DOjgcQfZDEQm6iE4ZsA9dCStOUdYVWXucKbDSe1I2twb7BrdqUS7tNZpyTx1ljhbp+gR6SAnc8ruKyxV5LqsLb83CGln5DyukdtA2y8SxHPXDuyhyXNy/S7NOj5P8zI43BNig+jMGpoNvPHkOoNTMcuqtzOv9r0FK5TsA9RDKgEOtI39oHNkoD7HA/8+VSmv/TV+0DTz/pDnqZILZlRtUEJzZxSu+mgNx3A9mC6QhaDtpR73bC5VhOw5rXbF2huFeYWN1fwEeAUxIugK0v7xvbydgolEzkIltCiBliDSzuRtmtT+OalAwwEFH5OuSCciGe+EDYhHX3svCGNlbYUAmVI1lKDtZ9EWe8pKElQEKt9bzXKV1NRA89YAhb8GR0LS5osj3mBAk3+rhQC0AbtxetKkvQnxHepbYZTo8iq0jcwsxtBLIVzgGUcuAOxgzLhy0gcOZgCQuhD4EvlsF4r0KNTvDEgoc6D99KSznKhMiEIv8xzICSlyGQh1qlWh7FEmO7TnNABv9EuD1Fd7m7cC1CwH/X1XOazz7TgTP1k6PgMIPb1wDqudkcRy1+NYzYHmhQzrh4F0eAebxIRSO0AnlcPTFLwlfTBI+x7Q+ZgujyqhUyx1prPqJyaGHgtTJZt7faTjeFcSOQXkE5p6S/Opr35R5G3OlC/UP3lTonaxZH+SpXy4NGdDKOO4GbcRvxinxKRA28Jx/58IMv s/rCRhVD zV0kGP2G+yCwmyan4PDjOahW7dZwHRClarwHI4w2f4y/r+8fJgaTuQwUbiDosN3HUXhWUSGRDpgyU3uDx1pIRVgH4JNBv0NFn0Td2pHXXzTDIAlCFPQIVhK9Ximla0sZTw/0bGxjrlIA6YqWVWUwI8IcCP35Ty2nn3bNCbuJZ+GLdGMPYiSlGKrRPeTiE6HEjNHwa/56uRD23L4SImBhdtgG0J4aI5Yl/Mk/wQsFdlrB6N9AXYchfAjmD4e2u9QHRkhewgK+HJKGOZdlz2eltlAI95uJ4Kl1fkHtLQkaPTkcQ+d1Y1KfRD/vTRjIvIDRsM5IYS+qCMF0T9MOH7JoKwT6xdyDCsLqFzfw0WwFgr1IC8b7DDktCccqJKX6YoYxvqdTeP0xtQ2ewvjvF5wZmsZ79MD28aHqf/zEX X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Feb 20, 2025 at 09:49:52AM +0800, Dave Young wrote: > On Wed, 19 Feb 2025 at 21:55, Alexander Graf wrote: > > >>> What architecture exactly does this KHO work fine? Device Tree > > >>> should be ok on arm*, x86 and power*, but how about s390? > > >> KHO does not use device tree as the boot protocol, it uses FDT as a data > > >> structure and adds architecture specific bits to the boot structures to > > >> point to that data, very similar to how IMA_KEXEC works. > > >> > > >> Currently KHO is implemented on arm64 and x86, but there is no fundamental > > >> reason why it wouldn't work on any architecture that supports kexec. > > > Well, the problem is whether there is a way to add dtb in the early > > > boot path, for X86 it is added via setup_data, if there is no such > > > way I'm not sure if it is doable especially for passing some info for > > > early boot use. Then the KHO will be only for limited use cases. > > > > > > Every architecture has a platform specific way of passing data into the > > kernel so it can find its command line and initrd. S390x for example has > > struct parmarea. To enable s390x, you would remove some of its padding > > and replace it with a KHO base addr + size, so that the new kernel can > > find the KHO state tree. > > Ok, thanks for the info, I cced s390 people maybe they can provide inputs. If I understand correctly, the parmarea would be used for passing the FDT address - which appears to be fine. However, s390 does not implement early_memremap()/early_memunmap(), which KHO needs. Thanks, Dave!