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authorLinus Torvalds <torvalds@linux-foundation.org>2020-06-01 23:35:27 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-01 23:35:27 +0300
commit58ff3b7604a461a766a84348e620834dce9834a9 (patch)
tree55aa2f96f7d342ceeaa377a0095f1c1cfe00b6ad /Documentation
parenta7092c82042b4ba3000cf7b369d1032161c5d4c9 (diff)
parente9524fb97ab5b41b85e1d3408f8e513433798f3c (diff)
downloadlinux-58ff3b7604a461a766a84348e620834dce9834a9.tar.xz
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 ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/fb/efifb.rst38
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>