docs: Add notes about UEFI features

Document that only UEFI booting is supported, the current status of
Secure Boot, and that the shell and networking are disabled.

Signed-off-by: Tim Crawford <tcrawford@system76.com>
This commit is contained in:
Tim Crawford
2021-12-21 10:32:37 -07:00
committed by Tim Crawford
parent 9c63db4c9f
commit 8c88ca0252

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# UEFI
System76 uses [EDK2](https://github.com/tianocore/edk2) to implement UEFI.
[coreboot](https://coreboot.org/) is used for Platform Initialization (PI).
## Booting
System76 Open Firmware only supports UEFI booting. Legacy BIOS-MBR booting is
not supported. `\EFI\BOOT\BOOTX64.EFI` must exist on the EFI System Partition
to be considered valid.
Network functionality is disabled. Native PXE booting is not supported.
### Secure Boot
Secure Boot support is currently disabled.
The implementation from 9elements is in development. If building a custom
image, the edk2 config `SECURE_BOOT_ENABLE` can be set to enable support.
There is currently no firmware UI to view or configure Secure Boot.
## Shell
The internal UEFI shell is disabled. A separate binary on a bootable drive
must be used to access the shell environment.