3. Boot Manager

3.1. Boot Manager

The Boot Manager in DXE executes after all the DXE drivers whose dependencies have been satisfied have been dispatched by the DXE Dispatcher. At that time, control is handed to the Boot Device Selection (BDS) phase of execution. The BDS phase is responsible for implementing the platform boot policy. System firmware that is compliant with this specification must implement the boot policy specified in the Boot Manager chapter of the UEFI 2.0 specification. This boot policy provides flexibility that allows system vendors to customize the user experience during this phase of execution.

The Boot Manager must also support booting from a short-form device path that starts with the first node being a firmware volume device path. The boot manager must use the GUID in the firmware volume device node to match it to a firmware volume in the system. The GUID in the firmware volume device path is compared with the firmware volume name GUID. If a match is made, then the firmware volume device path can be appended to the device path of the matching firmware volume and normal boot behavior can then be used.

The BDS phase is implemented as part of the BDS Architectural Protocol. The DXE Foundation will hand control to the BDS Architectural Protocol after all of the DXE drivers whose dependencies have been satisfied have been loaded and executed by the DXE Dispatcher. The BDS phase is responsible for the following:

• Initializing console devices

• Loading device drivers

• Attempting to load and execute boot selections

If the BDS phase cannot make forward progress, it will reinvoke the DXE Dispatcher to see if the dependencies of any additional DXE drivers have been satisfied since the last time the DXE Dispatcher was invoked.