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Wed, 26 Nov 2025 06:08:06 -0500 (EST) Date: Wed, 26 Nov 2025 11:08:05 +0000 From: Kiryl Shutsemau To: "Pratik R. Sampat" Cc: linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-efi@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, ardb@kernel.org, akpm@linux-foundation.org, david@redhat.com, osalvador@suse.de, thomas.lendacky@amd.com, michael.roth@amd.com Subject: Re: [RFC PATCH 1/4] efi/libstub: Decouple memory bitmap from the unaccepted table Message-ID: References: <20251125175753.1428857-1-prsampat@amd.com> <20251125175753.1428857-2-prsampat@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251125175753.1428857-2-prsampat@amd.com> X-Rspamd-Queue-Id: 749FF4001B X-Rspamd-Server: rspam02 X-Stat-Signature: mmk9kxuwg8pashgcdp4c1xciyxg5capi X-Rspam-User: X-HE-Tag: 1764155289-865996 X-HE-Meta: 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 15682nrA AB3RKnGOPAK4u2byhLBhuWHGlHpcd+jSV4X9vpMvJqN4uEKXVbJC2tPQdw3ey5zYB2GBOSOb6DG5NYtpHSQXrPCimnk97qujiw9urPcerLdsN3xJKkcSCTAu4C6y8AcvIdl6A10IHgb5DB7CuPU56K7OhOkngxhFh9eXRQe1dOT5woHiE2uD+Jzc0sCYIsPYWasW6f3EYrwgiRLCwn4u6up6pLm3Mbk3BHIcI3hV4Utx5n1+VJZujsJKP2TSB7b2h38pBJx3l8+uITWXJlxaNlNQ0bA== 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 Tue, Nov 25, 2025 at 11:57:50AM -0600, Pratik R. Sampat wrote: > Memory hotplug in secure environments requires the unaccepted memory > bitmap to grow as new memory is added. Currently, the bitmap is > implemented as a flexible array member at the end of struct > efi_unaccepted_memory, which is reserved by memblock at boot and cannot > be resized without reallocating the entire structure. > > Replace the flexible array member with a pointer. Well, it break interoperability between kernel before and after the patch. Consider kexec from kernel without the patch to the kernel with the patch and then back to older kernel. It is ABI break. Is re-allocating the entire structure such a big pain? -- Kiryl Shutsemau / Kirill A. Shutemov