[PATCH RESEND] Documentation: admin-guide: fix a doc for efi_no_storage_paranoia the "5KB" instead of the "50%"

[PATCH RESEND] Documentation: admin-guide: fix a doc for efi_no_storage_paranoia the "5KB" instead of the "50%"

[Koki Iwata]

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This percentage-based explanation has been outdated since commit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

Re: [PATCH RESEND] Documentation: admin-guide: fix a doc for efi_no_storage_paranoia the "5KB" instead of the "50%"

[Ard Biesheuvel]

On Fri, 10 Jul 2026, at 08:22, Koki Iwata wrote:
> 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>

Acked-by: Ard Biesheuvel <ardb@kernel.org>


> ---
>  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