efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation

Move the x86 EFI earlyprintk implementation to a shared location under
drivers/firmware and tweak it slightly so we can expose it as an earlycon
implementation (which is generic) rather than earlyprintk (which is only
implemented for a few architectures)

This also involves switching to write-combine mappings by default (which
is required on ARM since device mappings lack memory semantics, and so
memcpy/memset may not be used on them), and adding support for shared
memory framebuffers on cache coherent non-x86 systems (which do not
tolerate mismatched attributes).

Note that 32-bit ARM does not populate its struct screen_info early
enough for earlycon=efifb to work, so it is disabled there.

Signed-off-by: Ard Biesheuvel <[email protected]>
Reviewed-by: Alexander Graf <[email protected]>
Cc: AKASHI Takahiro <[email protected]>
Cc: Bjorn Andersson <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Heinrich Schuchardt <[email protected]>
Cc: Jeffrey Hugo <[email protected]>
Cc: Lee Jones <[email protected]>
Cc: Leif Lindholm <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Matt Fleming <[email protected]>
Cc: Peter Jones <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sai Praneeth Prakhya <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions