• Borislav Petkov's avatar
    x86/efi: Runtime services virtual mapping · d2f7cbe7
    Borislav Petkov authored
    We map the EFI regions needed for runtime services non-contiguously,
    with preserved alignment on virtual addresses starting from -4G down
    for a total max space of 64G. This way, we provide for stable runtime
    services addresses across kernels so that a kexec'd kernel can still use
    them.
    
    Thus, they're mapped in a separate pagetable so that we don't pollute
    the kernel namespace.
    
    Add an efi= kernel command line parameter for passing miscellaneous
    options and chicken bits from the command line.
    
    While at it, add a chicken bit called "efi=old_map" which can be used as
    a fallback to the old runtime services mapping method in case there's
    some b0rkage with a particular EFI implementation (haha, it is hard to
    hold up the sarcasm here...).
    
    Also, add the UEFI RT VA space to Documentation/x86/x86_64/mm.txt.
    Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
    Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
    d2f7cbe7
mm.txt 1.49 KB