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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2019-02-02 12:41:18 +0300
committerIngo Molnar <mingo@kernel.org>2019-02-04 10:27:30 +0300
commit69c1f396f25b805aeff08f06d2e992c315ee5b1e (patch)
tree7463653c8bd95300d4ae5697f00a4e061f8c613d /Documentation/admin-guide
parentce9084ba0d1d8030adee7038ace32f8d9d423d0f (diff)
downloadlinux-69c1f396f25b805aeff08f06d2e992c315ee5b1e.tar.xz
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 <ard.biesheuvel@linaro.org> Reviewed-by: Alexander Graf <agraf@suse.de> Cc: AKASHI Takahiro <takahiro.akashi@linaro.org> Cc: Bjorn Andersson <bjorn.andersson@linaro.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Heinrich Schuchardt <xypron.glpk@gmx.de> Cc: Jeffrey Hugo <jhugo@codeaurora.org> Cc: Lee Jones <lee.jones@linaro.org> Cc: Leif Lindholm <leif.lindholm@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Jones <pjones@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20190202094119.13230-10-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt8
1 files changed, 7 insertions, 1 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b799bcf67d7b..76dd3baa31e0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1073,9 +1073,15 @@
specified address. The serial port must already be
setup and configured. Options are not yet supported.
+ efifb,[options]
+ Start an early, unaccelerated console on the EFI
+ memory mapped framebuffer (if available). On cache
+ coherent non-x86 systems that use system memory for
+ the framebuffer, pass the 'ram' option so that it is
+ mapped with the correct attributes.
+
earlyprintk= [X86,SH,ARM,M68k,S390]
earlyprintk=vga
- earlyprintk=efi
earlyprintk=sclp
earlyprintk=xen
earlyprintk=serial[,ttySn[,baudrate]]