Bug#1110565: EFI runtime services not available in RT kernel
Control: reassign -1 src:linux
Control: forcemerge 956752 -1
On Fri, Aug 08, 2025 at 08:05:56PM +0200, Information BravoSystems wrote:
> Package: linux-image-rt-amd64
> Version: 6.12.38+deb13-rt
> Severity: normal
>
> EFI runtime services are not available when booting RT kernel,
> causing applications that depend on EFI variables to fail.
>
> Steps to reproduce:
> 1. Boot RT kernel
> 2. Check: ls /sys/firmware/efi/efivars/
> 3. Result: Empty
>
> Expected: EFI variables should be accessible like in non-RT kernel
>
> Additional info:
> - Non-RT kernel works fine
> - CONFIG_EFIVAR_FS=m in both kernels
> - CONFIG_EFI_DISABLE_RUNTIME is not set in RT kernel
> - Same hardware, different behavior
>
> When comparing
>
> grep -E "CONFIG_EFI*" /boot/config-6.12.38+deb13-rt-amd64
>
> against to
>
> grep -E "CONFIG_EFI*" /boot/config-6.12.38+deb13-amd64
>
> The result is,
>
> debian13:~$ diff config-efi-rt.txt config-efi-no-rt.txt
> 21c21
> < CONFIG_EFI_DISABLE_RUNTIME=y
> ---
> > # CONFIG_EFI_DISABLE_RUNTIME is not set
>
> Conclusion, On RT kernels seems that CONFIG_EFI_DISABLE_RUNTIME is not set.
This should be the same as #956752 . There is a documented workaround
which you can try in https://bugs.debian.org/1021245#10 .
Regards,
Salvatore
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