s because the 64-bit version of efi_ioremap calls init_memory_mapping for all addresses, regardless of whether they are RAM or MMIO. The EFI tables on this machine ask for runtime access to some MMIO regions: [ 0.000000] EFI: mem195: type=11, attr=0x8000000000000000, range=[0x0000000093400000-0x0000000093401000) (0MB) [ 0.000000] EFI: mem196: type=11, attr=0x8000000000000000, range=[0x00000000ffc00000-0x00000000ffc40000) (0MB) [ 0.000000] EFI: mem197: type=11, attr=0x8000000000000000, range=[0x00000000ffc40000-0x00000000ffc80000) (0MB) [ 0.000000] EFI: mem198: type=11, attr=0x8000000000000000, range=[0x00000000ffc80000-0x00000000ffca4000) (0MB) [ 0.000000] EFI: mem199: type=11, attr=0x8000000000000000, range=[0x00000000ffca4000-0x00000000ffcb4000) (0MB) [ 0.000000] EFI: mem200: type=11, attr=0x8000000000000000, range=[0x00000000ffcb4000-0x00000000ffffc000) (3MB) [ 0.000000] EFI: mem201: type=11, attr=0x8000000000000000, range=[0x00000000ffffc000-0x0000000100000000) (0MB) This arranges to pass the EFI memory type through to efi_ioremap, and makes efi_ioremap use ioremap rather than init_memory_mapping if the type is EFI_MEMORY_MAPPED_IO. With this, the above warning goes away. Signed-off-by: Paul Mackerras LKML-Reference: <19062.55858.533494.471153@cargo.ozlabs.ibm.com> Cc: Huang Ying Signed-off-by: H. Peter Anvin ð–ÙJŸAx