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X-CSE-ConnectionGUID: aNL5mkDZRZKHm2MChIVwIg== X-CSE-MsgGUID: Jcnc4CEuSDuZEPjytg5dHw== X-IronPort-AV: E=McAfee;i="6700,10204,11417"; a="47579121" X-IronPort-AV: E=Sophos;i="6.15,247,1739865600"; d="scan'208";a="47579121" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2025 15:19:48 -0700 X-CSE-ConnectionGUID: 6Z9gUdOPStqreZv11VO1qA== X-CSE-MsgGUID: ENdl0VpvQLumY0kFhj6Q4w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,247,1739865600"; d="scan'208";a="138440705" Received: from mdroper-mobl2.amr.corp.intel.com (HELO [10.124.222.199]) ([10.124.222.199]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2025 15:19:45 -0700 Message-ID: <8a57310a-dc4c-4ba2-9bc3-a16bc88ee4c5@intel.com> Date: Mon, 28 Apr 2025 15:19:43 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 00/14] kexec: introduce Kexec HandOver (KHO) To: Changyuan Lyu , linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, anthony.yznaga@oracle.com, arnd@arndb.de, ashish.kalra@amd.com, benh@kernel.crashing.org, bp@alien8.de, catalin.marinas@arm.com, corbet@lwn.net, dave.hansen@linux.intel.com, devicetree@vger.kernel.org, dwmw2@infradead.org, ebiederm@xmission.com, graf@amazon.com, hpa@zytor.com, jgowans@amazon.com, kexec@lists.infradead.org, krzk@kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, luto@kernel.org, mark.rutland@arm.com, mingo@redhat.com, pasha.tatashin@soleen.com, pbonzini@redhat.com, peterz@infradead.org, ptyadav@amazon.de, robh@kernel.org, rostedt@goodmis.org, rppt@kernel.org, saravanak@google.com, skinsburskii@linux.microsoft.com, tglx@linutronix.de, thomas.lendacky@amd.com, will@kernel.org, x86@kernel.org References: <20250411053745.1817356-1-changyuanl@google.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/10/25 22:37, Changyuan Lyu wrote: > When the actual kexec happens, the fdt is part of the image > set that we boot into. In addition, we keep "scratch regions" available > for kexec: physically contiguous memory regions that are guaranteed to > not have any memory that KHO would preserve. The new kernel bootstraps > itself using the scratch regions and sets all handed over memory as in use. > When drivers initialize that support KHO, they introspect the fdt, restore > preserved memory regions, and retrieve their states stored in the preserved > memory. It would be nice to have some bit of this blurb in the per-arch changelogs. It's not clear what the scratch regions are and how they are being used in the early boot code. Even a pointer over to the Documentation/ would be appreciated.