Intel Extensible Firmware Interface - Manual (Page 136)

Extensible Firmware Interface Specification
5-38 12/01/02 Version 1.10
UninstallProtocolInterface()
Summary
Removes a protocol interface from a device handle.
Prototype
typedef
EFI_STATUS
UninstallProtocolInterface (
IN EFI_HANDLE Handle,
IN EFI_GUID *Protocol,
IN VOID *Interface
);
Parameters
Handle The handle on which the interface was installed. If Handle is not a
valid handle, then EFI_INVALID_PARAMETER is returned. Type
EFI_HANDLE is defined in the InstallProtocolInterface()
function description.
Protocol The numeric ID of the interface. It is the caller’s responsibility to pass in
a valid GUID. See “Wired For Management Baseline” for a description
of valid GUID values. Type
EFI_GUID is defined in the
InstallProtocolInterface() function description.
Interface A pointer to the interface. NULL can be used if a structure is not
associated with Protocol .
Description
The UninstallProtocolInterface() function removes a protocol interface from the
handle on which it was previously installed. The Protocol and Interface values define the
protocol interface to remove from the handle.
The caller is responsible for ensuring that there are no references to a protocol interface that has
been removed. In some cases, outstanding reference information is not available in the protocol, so
the protocol, once added, cannot be removed. Examples include Console I/O, Block I/O, Disk I/O,
and (in general) handles to device protocols.
If the last protocol interface is removed from a handle, the handle is freed and is no longer valid.
EFI 1.10 Extension
The extension to this service directly addresses the limitations described in the section above.
There may be some drivers that are currently consuming the protocol interface that needs to be
uninstalled, so it may be dangerous to just blindly remove a protocol interface from the system.
Since the usage of protocol interfaces is now being tracked for components that use the
OpenProtocol() and CloseProtocol() boot services, a safe version of this function can be
implemented. Before the protocol interface is removed, an attempt is made to force all the drivers
that are consuming the protocol interface to stop consuming that protocol interface. This is done by
looping through all the drivers that currently have the protocol interface open with an attribute of
EFI_OPEN_PROTOCOL_BY_DRIVER or EFI_OPEN_PROTOCOL_BY_DRIVER |