• Ard Biesheuvel's avatar
    efi/loongarch: libstub: remove dependency on flattened DT · 40cd01a9
    Ard Biesheuvel authored
    LoongArch does not use FDT or DT natively [yet], and the only reason it
    currently uses it is so that it can reuse the existing EFI stub code.
    
    Overloading the DT with data passed between the EFI stub and the core
    kernel has been a source of problems: there is the overlap between
    information provided by EFI which DT can also provide (initrd base/size,
    command line, memory descriptions), requiring us to reason about which
    is which and what to prioritize. It has also resulted in ABI leaks,
    i.e., internal ABI being promoted to external ABI inadvertently because
    the bootloader can set the EFI stub's DT properties as well (e.g.,
    "kaslr-seed"). This has become especially problematic with boot
    environments that want to pretend that EFI boot is being done (to access
    ACPI and SMBIOS tables, for instance) but have no ability to execute the
    EFI stub, and so the environment that the EFI stub creates is emulated
    [poorly, in some cases].
    
    Another downside of treating DT like this is that the DT binary that the
    kernel receives is different from the one created by the firmware, which
    is undesirable in the context of secure and measured boot.
    
    Given that LoongArch support in Linux is brand new, we can avoid these
    pitfalls, and treat the DT strictly as a hardware description, and use a
    separate handover method between the EFI stub and the kernel. Now that
    initrd loading and passing the EFI memory map have been refactored into
    pure EFI routines that use EFI configuration tables, the only thing we
    need to pass directly is the kernel command line (even if we could pass
    this via a config table as well, it is used extremely early, so passing
    it directly is preferred in this case.)
    Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
    Acked-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
    40cd01a9
bootinfo.h 1012 Bytes