On Mon, Nov 18, 2019 at 04:21:18PM -0800, Sean Christopherson wrote: > Through a labyrinthian sequence of includes, usage of virt_to_phys() is > dependent on the include of asm/io.h in x86's asm/realmode.h, which is > included in x86's asm/acpi.h and thus by linux/acpi.h. Explicitly > include linux/io.h to break the dependency on realmode.h so that a > future patch can remove the realmode.h include from acpi.h without > breaking the build. Acked-by: Mark Brown