What is efifb?¶
This is a generic EFI platform driver for systems with UEFI firmware. Thesystem must be booted via the EFI stub for this to be usable. efifb supportsboth firmware with Graphics Output Protocol (GOP) displays as well as oldersystems with only Universal Graphics Adapter (UGA) displays.
Supported Hardware¶
- iMac 17”/20”
- Macbook
- Macbook Pro 15”/17”
- MacMini
- ARM/ARM64/X86 systems with UEFI firmware
How to use it?¶
For UGA displays, efifb does not have any kind of autodetection of yourmachine.
You have to add the following kernel parameters in your elilo.conf:
Macbook : video=efifb:macbookMacMini : video=efifb:miniMacbook Pro 15", iMac 17" : video=efifb:i17Macbook Pro 17", iMac 20" : video=efifb:i20
For GOP displays, efifb can autodetect the display’s resolution and framebufferaddress, so these should work out of the box without any special parameters.
Accepted options:
| nowc | Don’t map the framebuffer write combined. This can be usedto workaround side-effects and slowdowns on other CPU coreswhen 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 ifpossible.
- <xres>x<yres>[-(rgb|bgr|<bpp>)]
- The EFI stub will search for a display mode that matches the specifiedhorizontal and vertical resolution, and optionally bit depth, and setthe 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 numberfor a mode with matching bits per pixel.
- auto
- The EFI stub will choose the mode with the highest resolution (productof horizontal and vertical resolution). If there are multiple modeswith the highest resolution, it will choose one with the highest colordepth.
- list
- The EFI stub will list out all the display modes that are available. Aspecific mode can then be chosen using one of the above options for thenext boot.
Edgar Hucek <gimli@dark-green.com>