5.2 Services that UEFI drivers rarely use
Table 19 lists UEFI services rarely used by UEFI drivers. The following sub-topics briefly describe each service, why they are rarely used, or the particular circumstance in which they are useful. The code examples show how the services are typically used by UEFI drivers and are grouped by Service Type.

Table 19-UEFI services that are rarely used by UEFI drivers

Service
Type
Service Type
Notes
ConnectController()
Boot
Protocol Handler
Uses a set of precedence rules to find the best set of drivers to manage a controller.
DisconnectController()
Boot
Protocol Handler
Informs a set of drivers to stop managing a controller.
ReinstallProtocolInterface()
Boot
Protocol Handler
Reinstalls a protocol interface on a device handle.
LocateDevicePath()
Boot
Protocol Handler
Locates a device handle supporting a specific protocol and having the closest matching device path. UEFI drivers should use the services on the ControllerHandle passed into the Supported() and Start() functions of the driver's EFI_DRIVER_BINDING_PROTOCOL.
LoadImage()
Boot
Image
Used only by bus drivers that can load, start, and potentially unload UEFI drivers stored in other images in some other location on the child devices of the bus.
StartImage()
Boot
Image
Used only by bus drivers that can load, start, and potentially unload UEFI drivers stored in other images in some other location on the child devices of the bus.
GetVariable()
Runtime
Variable
Returns the value of a variable.
SetVariable()
Runtime
Variable
Sets the value of a variable.
QueryVariableInfo()
Runtime
Variable
Returns information about the EFI variables.
GetTime()
Runtime
Time-related
Returns the current time and date, and the time-keeping capabilities of the platform.
CalculateCrc32()
Boot
Miscellaneous
Maintains the checksum of the UEFI System Table, UEFI boot services table, and UEFI runtime services table.
ConvertPointer()
Runtime
Miscellaneous
Sometimes used by UEFI runtime drivers. This service should never be used by UEFI boot service drivers.
InstallConfigurationTable()
Boot
Miscellaneous
Adds, updates, or removes a configuration table from the UEFI system table.
WaitForEvent()
Boot
Event
Stops execution until an event is signaled.
GetNextMonotonicCount()
Boot
Special
Provides a 64-bit monotonic counter that is guaranteed to increase.
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