5.1 Services that UEFI drivers commonly use
The following table lists UEFI services commonly used by UEFI drivers. Following that, discussions briefly describe each service, why they are commonly used, or the particular circumstance in which they are useful. Code examples show how the services are typically used by UEFI drivers and are grouped by Service Type.

Table 18-UEFI services that are commonly used by UEFI drivers

Service
Type
Service Type
Description
AllocatePool()
Boot
Memory Allocation
Allocates a memory buffer of a particular type.
FreePool()
Boot
Memory Allocation
Frees a previously allocated memory buffer.
AllocatePages()
Boot
Memory Allocation
Allocates one memory buffer of a particular type with a 4KB aligned start address and a 4KB aligned length.
FreePages()
Boot
Memory Allocation
Frees a memory buffer previously allocated with AllocatePages().
CopyMem()
Boot
Miscellaneous
Copies a buffer from one location to another.
SetMem()
Boot
Miscellaneous
Initializes the contents of a buffer with a specified value.
InstallMultipleProtocolInterfa ces()
Boot
Protocol Handler
Installs one or more protocol interfaces onto a handle. Replaces the InstallProtocolInterface() service.
UninstallMultipleProtocolInter faces()
Boot
Protocol Handler
Uninstalls one or more protocol interfaces from a handle. Replaces the UninstallProtocolInterface() service.
LocateHandleBuffer()
Boot
Protocol Handler
Retrieves a list of handles from the handle database meeting the search criteria. The return buffer is automatically allocated.
LocateProtocol()
Boot
Protocol Handler
Finds the first handle in the handle database supporting the requested protocol.
OpenProtocol()
Boot
Protocol Handler
Adds elements to the list of agents consuming a protocol interface.
OpenProtocolInformation()
Boot
Protocol Handler
Retrieves the list of agents currently consuming a protocol interface.
CloseProtocol()
Boot
Protocol Handler
Removes elements from the list of agents consuming a protocol interface.
RaiseTPL()
Boot
Task Priority
Raises the task priority level.
RestoreTPL()
Boot
Task Priority
Restores/lowers the task priority level.
CreateEvent()
Boot
Event
Creates a general-purpose event structure.
CreateEventEx()
Boot
Event
Creates an event structure as part of an event group. This service is new.
CloseEvent()
Boot
Event
Closes and frees an event structure.
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