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X-IronPort-AV: E=McAfee;i="6600,9927,10847"; a="872794" X-IronPort-AV: E=Sophos;i="6.03,187,1694761200"; d="scan'208";a="872794" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2023 03:13:33 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10847"; a="749914451" X-IronPort-AV: E=Sophos;i="6.03,187,1694761200"; d="scan'208";a="749914451" Received: from mziotti-mobl4.ger.corp.intel.com (HELO box.shutemov.name) ([10.249.34.13]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2023 03:13:27 -0700 Received: by box.shutemov.name (Postfix, from userid 1000) id B9E791095FB; Fri, 29 Sep 2023 13:13:24 +0300 (+03) Date: Fri, 29 Sep 2023 13:13:24 +0300 From: "Shutemov, Kirill" To: Stanislav Kinsburskii Cc: Dave Hansen , Baoquan He , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, ebiederm@xmission.com, akpm@linux-foundation.org, stanislav.kinsburskii@gmail.com, corbet@lwn.net, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, kys@microsoft.com, jgowans@amazon.com, wei.liu@kernel.org, arnd@arndb.de, gregkh@linuxfoundation.org, graf@amazon.de, pbonzini@redhat.com Subject: Re: [RFC PATCH v2 0/7] Introduce persistent memory pool Message-ID: <20230929101324.jgixt4jmqialchno@box.shutemov.name> References: <20230927161319.GA19976@skinsburskii.> <20230927232548.GA20221@skinsburskii.> <20230928000230.GA20259@skinsburskii.> <760bbb08-83b4-7bb1-822f-2ceba26278a6@intel.com> <20230928003831.GA20366@skinsburskii.> <340596c9-d55d-5f8a-fa27-d95b0e10b20a@intel.com> <20230928024636.GA20423@skinsburskii.> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230928024636.GA20423@skinsburskii.> X-Rspamd-Queue-Id: 9DD9EC0002 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: hy9thipmicc948rb6n7j9u7cscqwmzo5 X-HE-Tag: 1695982414-854396 X-HE-Meta: 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 233IWzyg XRetGrgUm8lQHzSr1D3aQl94S8ETmX12V0TSzzIJQqBWrBZKWMOI+SKvqcX5nOOmMN+jMl34U/5G3BhWBoFpsG5PtGrDAwpHo6W/RSnxZctHYcqf/mfr3Xp7W0JIS8cZ+sHUwJOlfcWTZcK5Zwd7knNFyUxA2BptGewr6SQXQnQWyJ5+x67FfWLFn0XCuh9sIF2eSACRlT6UO/CJirrqR4dfe4Ds4JmFoBJv+MTk3S/bfyLchdFXqIF+hcTmKeBKq6ZxTpeIsQ8GADcP/E6EMTBAwjd38GpMRu5k0YqKb6ASqliKXMxu9MkTtGFdYMpeC+xRs2zPTcO0KmJfzYidYLaHo8UODp4Yiu9Dze+3mawExVSy5FpDVme/acA== 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: On Wed, Sep 27, 2023 at 07:46:36PM -0700, Stanislav Kinsburskii wrote: > I'd answer yes, "System MAP" must be persisted across kexec. > Could you elaborate on why there should be a mechanism to tell the > kernel anything special about the existent "System map" in this context? > Say, one can reserve a CMA region (or a crash kernel region, etc), store > there some data, and then pass it across kexec. Reserved CMA region will > still be a part of the "System MAP", won't it? Em. When crash kernel starts all System RAM of the the first kernel becomes E820_TYPE_RESERVED and only memory pre-allocated for crash scenario becomes E820_TYPE_RAM. See crash_setup_memmap_entries(). Can't you go the same path? Report all deposited memory as E820_TYPE_RESERVED. Or do you have too many deposited memory ranges, so we would run out of e820 entries? -- Kiryl Shutsemau / Kirill A. Shutemov