UefiFallbackMode
UEFI fallback mode
UEFI provides a mechanism for booting from an EFI file without a corresponding boot variable existing in NVRAM. This is known as the UEFI fallback mode, and it uses a specific file path (/EFI/BOOT) to locate the fallback bootloader.
This configuration option allows specifying how Trident should populate the UEFI fallback boot files during OS installation or update.
| Characteristic | Value |
|---|---|
| Type | enum |
Variants
Conservative
During clean install, the UEFI fallback will be updated during finalize to boot to the target OS. During an A/B update, the UEFI fallback will be updated to boot to the servicing OS (the existing OS) during finalize and then will be updated to boot to the target OS when commit validates the target OS as healthy. This aligns with how Trident handles the UEFI boot variables during an update.
| Characteristic | Value |
|---|---|
| Type | string |
| Value | conservative |
Optimistic
During clean install, the UEFI fallback will be updated during finalize to boot to the target OS. During an A/B update, the UEFI fallback will be updated to boot to the target OS (the newly installed OS) during the finalize stage.
| Characteristic | Value |
|---|---|
| Type | string |
| Value | optimistic |
Disabled
No UEFI fallback boot files are installed.
| Characteristic | Value |
|---|---|
| Type | string |
| Value | disabled |