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X-CSE-ConnectionGUID: 7jT1tFArTxS8pIYhlpt3wQ== X-CSE-MsgGUID: Hl5klvuIRkW1IBz/fOD9lg== X-IronPort-AV: E=McAfee;i="6700,10204,11417"; a="47579135" X-IronPort-AV: E=Sophos;i="6.15,247,1739865600"; d="scan'208";a="47579135" 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 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 X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: B4B57A0008 X-Rspam-User: X-Stat-Signature: qmqax6en6wsgo95wm33xu7xes3p1ho3z X-HE-Tag: 1745878789-956589 X-HE-Meta: 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 sTJ/TYHx wn1I1TBKAnH7DJUQKzMBRH52lNo2U39IaiuzCan+POwRlaOo/qwNmUZPzTBBDRXGzGwYIEOV8V/ROHFXsZajAvhyC1kfiKE1pgu187/nFiccTFIT/hMVcu4KpE7ZNXkX3yKDiQUOarivMYYGCjpFl5e8YeJvhIDDKb8nXZ24dLzCs+rXvKw1FonOKp5JO8uaJX1J5Dm1LJQ66WX0= 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 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.