| ============== | |
| What is efifb? | |
| ============== | |
| 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 | |
| ================== | |
| - 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 your | |
| machine. | |
| You have to add the following kernel parameters in your elilo.conf:: | |
| Macbook : | |
| video=efifb:macbook | |
| MacMini : | |
| video=efifb:mini | |
| Macbook Pro 15", iMac 17" : | |
| video=efifb:i17 | |
| 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: | |
| ======= =========================================================== | |
| nowc Don't map the framebuffer write combined. This can be used | |
| to workaround side-effects and slowdowns on other CPU cores | |
| 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> |