Objects of several differing types are managed through the services provided by UEFI. The following figure shows the various object types. The most important objects for UEFI drivers are the following:
UEFI system table
Some UEFI drivers may need to access environment variables, but most do not.
Rarely do UEFI drivers require the use of a monotonic counter, watchdog timer or realtime clock.
The UEFI system table provides access to all services provided by UEFI. The system table also provides access to all the additional data structures that describe the configuration of the platform. Each of these object types, and the services that provide access to them, are introduced in the following sections.