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Sat, 10 Oct 2026 08:41:42 -0700 (PDT) X-Received: by 2002:a05:620a:4510:b0:93e:c12c:f13a with SMTP id af79cd13be357-93ec12d0631mr714838485a.68.1791646901755; Sat, 10 Oct 2026 08:41:41 -0700 (PDT) Received: from [192.168.2.110] ([142.172.30.162]) by smtp.gmail.com with ESMTPSA id af79cd13be357-93eb9722fbasm453274285a.6.2026.10.10.08.41.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 10 Oct 2026 08:41:41 -0700 (PDT) Message-ID: <87f6a5de-7ba7-40e6-ad31-e1311033e986@redhat.com> Date: Sat, 10 Oct 2026 11:41:40 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] x86: remove the BIOS memory corruption check feature From: Luiz Capitulino To: Thorsten Blum Cc: LKML , Linux Memory Management List , x86@kernel.org, Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , corbet@lwn.net, hpa@zytor.com, "David Hildenbrand (Red Hat)" , Mike Rapoport References: <9e1a161e-9246-41d1-9651-ffa85b1bc99b@redhat.com> In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: jH6l6XS30jIJtSp4wgMQlHic-GuzFflc6oKDoWeHd1o_1791646902 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: BEC7E2000C X-Rspam-User: X-Stat-Signature: ib1anjikyrd7s1jpqkqaa15znyp44zxk X-HE-Tag: 1791646904-532386 X-HE-Meta: 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 mHJOW19D 89faCzogcY+OIOeK2hPii5Gxm+5cHs2lQVek4ChKPOW2XsVGRqPqO0APfXNgQs8+pr54wuekyR1mRIoUuFBY5GWX3VyAC/OHaoTmk+30arKa7raU2NdyphiVHS3Ryi2AUyYK4Cbw27FEpv45Wz5A59TDsOW4pXBFdyCTyAJ+KhMoIxy1wCxTHQwErtPeHcjESjkpM7RhgCycBBh82gWGc6TS+JIIHGfzBiTE8Qh1p7IX0BAAqxlg2X6AAd/JantkV41+moZg0LJfuSFuRShy0LszzM4ucWsJWS2zLGtPN1SBI8nrguFg43r9I09DwKcxGayDoi5N39k5gyemxiimVASn5RUxJ2ddHy3S28aVVztOt+BA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/9/26 4:16 PM, Luiz Capitulino wrote: > > > On 10/9/26 2:06 PM, Thorsten Blum wrote: >> On Mon, Jul 20, 2026 at 04:41:05PM -0400, Luiz Capitulino wrote: >>> By default, the BIOS memory corruption check works by reserving the >>> first 64 KiB physical area from memblock, zeroing it and then scanning it >>> periodically. >>> >>> However, this functionality has been broken since v5.13 by two commits: >>> >>> - Commit a799c2bd29d1 ("x86/setup: Consolidate early memory reservations"). >>> Moved trim_low_memory_range() into early_reserve_memory(), which runs >>> earlier in setup_arch(), causing the first 64 KiB to be reserved (when >>> CONFIG_X86_RESERVE_LOW=64) before setup_bios_corruption_check() runs >>> >>> - Commit f1d4d47c5851 ("x86/setup: Always reserve the first 1M of RAM"). >>> Hardcodes the reservation of the first 64 KiB early in >>> early_reserve_memory() >>> >>> It might be possible to get this feature to work by allowing >>> setup_bios_corruption_check() to run first, but it's just not worth it >>> given that the kernel will never access this memory area anyways. >>> >>> Signed-off-by: Luiz Capitulino >>> --- >>> >>> Changelog >>> ========= >>> >>> v2 >>> - Rebase against latest Linus tree (v7.2-rc4) >>> - Improve changelog >>> >>> .../admin-guide/kernel-parameters.txt | 23 --- >>> arch/x86/Kconfig | 30 --- >>> arch/x86/configs/i386_defconfig | 1 - >>> arch/x86/configs/x86_64_defconfig | 1 - >>> arch/x86/include/asm/bios_ebda.h | 17 -- >>> arch/x86/include/asm/setup.h | 1 - >>> arch/x86/kernel/Makefile | 2 - >>> arch/x86/kernel/check.c | 187 ------------------ >>> arch/x86/kernel/setup.c | 4 - >>> 9 files changed, 266 deletions(-) >>> delete mode 100644 arch/x86/kernel/check.c >> >> Hi Luiz, > > Hey, > >> v2 no longer applies to mainline - are you planning to rebase it for v3? > > If we plan to merge it, I can :) > >> Regarding the changelog: did you consider that the check is only broken >> for the default size? Booting with >> >> memory_corruption_check=1 memory_corruption_check_size=256K >> >> still works and I get: >> >> check: Scanning 1 areas for low memory corruption >> check: Scanning for low memory corruption every 60 seconds > > Yes, but IIRC this won't reserve the first 64K and my understanding > is that checking the first 64K was the main point of the feature. I've just sent v3. I improved the changelog based on your feedback. Also, I realized that v2 doesn't apply because it was mangled by my MUA. I sent v3 with git-send-email so it should apply now.