Intel Extensible Firmware Interface - Manual (Page 158)

Extensible Firmware Interface Specification
5-60 12/01/02 Version 1.10
Description
This function allocates and returns a buffer of EFI_OPEN_PROTOCOL_INFORMATION_ENTRY
structures. The buffer is returned in EntryBuffer , and the number of entries is returned in
EntryCount .
If the interface specified by Protocol is not supported by the handle specified by Handle , then
EFI_NOT_FOUND is returned.
If the interface specified by Protocol is supported by the handle specified by Handle , then
EntryBuffer is allocated with the boot service AllocatePool() , and EntryCount is set
to the number of entries in EntryBuffer . Each entry of EntryBuffer is filled in with the
image handle, controller handle, and attributes that were passed to OpenProtocol() when the
protocol interface was opened. The field OpenCount shows the number of times that the protocol
interface has been opened by the agent specified by ImageHandle , ControllerHandle , and
Attributes . After the contents of EntryBuffer have been filled in, EFI_SUCCESS is
returned. It is the caller’s responsibility to call FreePool() on EntryBuffer when the caller
no longer required the contents of EntryBuffer .
If there are not enough resources available to allocate EntryBuffer , then
EFI_OUT_OF_RESOURCES is returned.
Status Codes Returned
EFI_SUCCESS The open protocol information was returned in EntryBuffer , and the
number of entries was returned EntryCount .
EFI_NOT_FOUND Handle does not support the protocol specified by Protocol .
EFI_OUT_OF_RESOURCES There are not enough resources available to allocate EntryBuffer .
Examples
See example in the LocateHandleBuffer() function description for an example on how
LocateHandleBuffer() , ProtocolsPerHandle() , OpenProtocol() , and
OpenProtocolInformation() can be used to traverse the entire handle database.