Re: [PATCH] efi/x86-stub: store acpi_rsdp_addr in bootparams

[Ard Biesheuvel]

Hi Dave,

On Tue, 17 Feb 2026, at 09:04, Dave Young wrote:
> Kernel panic occurs during a kexec reboot when EFI runtime services
> are not enabled in the first kernel. The issue is that the second
> kernel cannot find the ACPI RSDP address during boot.
>
> In legacy boot, the acpi_rsdp_addr is set in early x86 boot code.
> However, kernel decompression has moved to the EFI stub for EFI boot.
> Therefore, the x86 EFI stub must also be updated to store the
> acpi_rsdp_addr in the boot parameters to ensure the kexec kernel
> can find it.
>
> (Note: If the pre-kexec kernel was itself a kexec boot, the later kexec
> reboot will still utilize the legacy decompressor path, so the original
> code remains functional though some cleanups can be done later.)
>
> Signed-off-by: Dave Young <dyoung@xxxxxxxxxx>
> ---
>  drivers/firmware/efi/libstub/x86-stub.c |   18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>

If this issue is kexec-specific, can we move this to where the kexec code prepares the boot_params struct for the next kernel?