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From: Koki Iwata <iwata.koki@fujitsu.com>
To: Jonathan Corbet <corbet@lwn.net>, Ard Biesheuvel <ardb@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>,
	Matthew Garrett <matthew.garrett@nebula.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Borislav Petkov <bp@alien8.de>,
	Randy Dunlap <rdunlap@infradead.org>,
	Thomas Gleixner <tglx@kernel.org>,
	Feng Tang <feng.tang@linux.alibaba.com>,
	Dapeng Mi <dapeng1.mi@linux.intel.com>,
	Marco Elver <elver@google.com>, Jakub Kicinski <kuba@kernel.org>,
	Eric Biggers <ebiggers@kernel.org>,
	Li RongQing <lirongqing@baidu.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Matt Fleming <mfleming@cloudflare.com>,
	linux-doc@vger.kernel.org, linux-efi@vger.kernel.org,
	linux-kernel@vger.kernel.org, iwata.koki@fujitsu.com
Subject: [PATCH RESEND] Documentation: admin-guide: fix a doc for efi_no_storage_paranoia the "5KB" instead of the "50%"
Date: Fri, 10 Jul 2026 15:22:44 +0900	[thread overview]
Message-ID: <20260710062306.1204206-1-iwata.koki@fujitsu.com> (raw)

From: Iwata Koki <iwata.koki@fujitsu.com>

The documentation for 'efi_no_storage_paranoia' incorrectly states
the kernel cannot use "more than 50%" of the EFI variable storage.

This percentage-based explanation has been outdated since commit
f8b8404337de ("Modify UEFI anti-bricking code") introduced a fixed 5KB
minimum reserve threshold (EFI_MIN_RESERVE) in
arch/x86/platform/efi/quirks.c. At that time, the documentation was not
updated to reflect this change.

Update the documentation to reflect the "5KB" instead of the "50%".

Fixes: f8b8404337de ("Modify UEFI anti-bricking code")
Signed-off-by: Koki Iwata <iwata.koki@fujitsu.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b5493a7f8f22..3f75969a679b 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1614,10 +1614,17 @@ Kernel parameters
 			on all PCI bridges while in the EFI boot stub
 
 	efi_no_storage_paranoia [EFI,X86,EARLY]
-			Using this parameter you can use more than 50% of
-			your efi variable storage. Use this parameter only if
-			you are really sure that your UEFI does sane gc and
-			fulfills the spec otherwise your board may brick.
+			The kernel reserves 5KB of EFI variable storage for
+			safety, because some UEFI implementation may fail to
+			boot if there's insufficient space in the EFI variable
+			storage.
+
+			Using this parameter, you can use the 5KB reservation
+			in the EFI variable storage.
+
+			However, Use this parameter only if you are really
+			sure that your UEFI does sane gc and fulfills the spec
+			otherwise your board may brick.
 
 	efivar_ssdt=	[EFI; X86] Name of an EFI variable that contains an SSDT
 			that is to be dynamically loaded by Linux. If there are
-- 
2.52.0


                 reply	other threads:[~2026-07-10  6:24 UTC|newest]

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