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b=Bi3Y+hEvxhTKGPnvRXnd/oWDFx1A1IKHvDWstaqyRbySmBo/iD9xB9FQnFGvSZCxc 65xQqNX7/iEWYesSg7DY9qV3ChEvsma6PZ4lENH5CjKXcFyuJE3LhNToIR0dbOwcsx GYIPvBmOokc9cWxxcZRJEtk9xDy9mwUkO/GVqUXtyxir3+cb5ykKcyoEZoFCuPBuvl xpyEHW21/P8TaujPzQ+mRVkaJAZ8HbDBQI6VRK0noggLtAGzJjraMq11zQ6d4oMxUy fL7xrTm9k0LqfJue2/vHPGlLLuFNhn9o2hyiWa0eo5/iSyvjpr9dAeYDiiDIM0jCiU nfxFcGPubISdA== Date: Fri, 9 Oct 2026 20:06:49 +0200 From: Thorsten Blum To: Luiz Capitulino 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 Subject: Re: [PATCH v2] x86: remove the BIOS memory corruption check feature Message-ID: References: <9e1a161e-9246-41d1-9651-ffa85b1bc99b@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9e1a161e-9246-41d1-9651-ffa85b1bc99b@redhat.com> X-Rspamd-Queue-Id: 1F907C000A X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 8saw839tn599r17myc1wymcy5wh9x5tp X-HE-Tag: 1791569215-810017 X-HE-Meta: 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 cuzGKN7u 0QEYOlCuF/msTflS1bUZcciF9Si6o0C2DwkKXtIrw2igx7R4rpACufTJQiQLninMUyrcjkVRuGh7LuNi4VBK6R+YLoNgUx7RAwx8w3eK/RTKXwz0Nedq/X2ka8SX1QH758nORpU7pUjNOcX0IQ1Y+bOEfsGHnENdqgb5uU5YAY7dSRZ9WhYLtD5eZFZVQmi5F7gKJWt9kD+9IPbUDthkeqWowxHA0lFdV7kQIw6E0UwNHmsJ0YuGQAexMcxDFTHwIlbLJyhdyJ93m+MzexaODCD3wuQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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, v2 no longer applies to mainline - are you planning to rebase it for v3? 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 Thanks, Thorsten