Kernel with CONFIG_EFI_ZBOOT not supported

[Heinrich Schuchardt]

We use GRUB 2.06 to load kernels with an EFI stub using the linux command. To ensure that the loaded EFI binary is really a kernel GRUB checks for specific bytes which are not defined by the EFI specification, e.g. on RISC-V it looks for GRUB_LINUX_RISCV_MAGIC_SIGNATURE ('RSC\0x05').

These checks have been removed in upstream GRUB with commits 69edb3120560 ("loader/arm64/linux: Remove magic number header field check") and 067bd35cd420 ("efi: Remove arch specific image headers for RISC-V, ARM64 and ARM").

When compiling the arm64 or riscv64 kernel with CONFIG_EFI_ZBOOT the kernel specific signatures are not exposed.

Please, adjust our GRUB to be compliant with the EFI specification and to support the upstream kernel.

Best regards

Heinrich