Merge tag 'efi-core-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull EFI updates from Ingo Molnar:
 "The EFI changes for this cycle are:

   - preliminary changes for RISC-V

   - Add support for setting the resolution on the EFI framebuffer

   - Simplify kernel image loading for arm64

   - Move .bss into .data via the linker script instead of relying on
     symbol annotations.

   - Get rid of __pure getters to access global variables

   - Clean up the config table matching arrays

   - Rename pr_efi/pr_efi_err to efi_info/efi_err, and use them
     consistently

   - Simplify and unify initrd loading

   - Parse the builtin command line on x86 (if provided)

   - Implement printk() support, including support for wide character
     strings

   - Simplify GDT handling in early mixed mode thunking code

   - Some other minor fixes and cleanups"

* tag 'efi-core-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (79 commits)
  efi/x86: Don't blow away existing initrd
  efi/x86: Drop the special GDT for the EFI thunk
  efi/libstub: Add missing prototype for PE/COFF entry point
  efi/efivars: Add missing kobject_put() in sysfs entry creation error path
  efi/libstub: Use pool allocation for the command line
  efi/libstub: Don't parse overlong command lines
  efi/libstub: Use snprintf with %ls to convert the command line
  efi/libstub: Get the exact UTF-8 length
  efi/libstub: Use %ls for filename
  efi/libstub: Add UTF-8 decoding to efi_puts
  efi/printf: Add support for wchar_t (UTF-16)
  efi/gop: Add an option to list out the available GOP modes
  efi/libstub: Add definitions for console input and events
  efi/libstub: Implement printk-style logging
  efi/printf: Turn vsprintf into vsnprintf
  efi/printf: Abort on invalid format
  efi/printf: Refactor code to consolidate padding and output
  efi/printf: Handle null string input
  efi/printf: Factor out integer argument retrieval
  efi/printf: Factor out width/precision parsing
  ...

1 files changed, 35 insertions, 3 deletions

diff --git a/Documentation/fb/efifb.rst b/Documentation/fb/efifb.rst
index 04840331a00e..6badff64756f 100644
--- a/Documentation/fb/efifb.rst
+++ b/Documentation/fb/efifb.rst
@@ -2,8 +2,10 @@
 What is efifb?
 ==============
 
-This is a generic EFI platform driver for Intel based Apple computers.
-efifb is only for EFI booted Intel Macs.
+This is a generic EFI platform driver for systems with UEFI firmware. The
+system must be booted via the EFI stub for this to be usable. efifb supports
+both firmware with Graphics Output Protocol (GOP) displays as well as older
+systems with only Universal Graphics Adapter (UGA) displays.
 
 Supported Hardware
 ==================
@@ -12,11 +14,14 @@ Supported Hardware
 - Macbook
 - Macbook Pro 15"/17"
 - MacMini
+- ARM/ARM64/X86 systems with UEFI firmware
 
 How to use it?
 ==============
 
-efifb does not have any kind of autodetection of your machine.
+For UGA displays, efifb does not have any kind of autodetection of your
+machine.
+
 You have to add the following kernel parameters in your elilo.conf::
 
 	Macbook :
@@ -28,6 +33,9 @@ You have to add the following kernel parameters in your elilo.conf::
 	Macbook Pro 17", iMac 20" :
 		video=efifb:i20
 
+For GOP displays, efifb can autodetect the display's resolution and framebuffer
+address, so these should work out of the box without any special parameters.
+
 Accepted options:
 
 ======= ===========================================================
@@ -36,4 +44,28 @@ nowc	Don't map the framebuffer write combined. This can be used
 	when large amounts of console data are written.
 ======= ===========================================================
 
+Options for GOP displays:
+
+mode=n
+        The EFI stub will set the mode of the display to mode number n if
+        possible.
+
+<xres>x<yres>[-(rgb|bgr|<bpp>)]
+        The EFI stub will search for a display mode that matches the specified
+        horizontal and vertical resolution, and optionally bit depth, and set
+        the mode of the display to it if one is found. The bit depth can either
+        "rgb" or "bgr" to match specifically those pixel formats, or a number
+        for a mode with matching bits per pixel.
+
+auto
+        The EFI stub will choose the mode with the highest resolution (product
+        of horizontal and vertical resolution). If there are multiple modes
+        with the highest resolution, it will choose one with the highest color
+        depth.
+
+list
+        The EFI stub will list out all the display modes that are available. A
+        specific mode can then be chosen using one of the above options for the
+        next boot.
+
 Edgar Hucek <gimli@dark-green.com>