uefi specifications example mentions EfiCoreImageHandle. How to get it? - c

Question

Quoting the UEFI specifications section about EFI_BOOT_SERVICES.HandleProtocol():
The HandleProtocol() function is still available for use by old EFI
applications and drivers. However, all new applications and drivers
should use EFI_BOOT_SERVICES.OpenProtocol() in place of
HandleProtocol(). The following code fragment shows a possible
implementation of HandleProtocol() using OpenProtocol(). The variable
EfiCoreImageHandle is the image handle of the EFI core.
EFI_STATUS
HandleProtocol (
IN EFI_HANDLE Handle,
IN EFI_GUID *Protocol,
OUT VOID **Interface
)
{
return OpenProtocol (
Handle,
Protocol,
Interface,
EfiCoreImageHandle,
NULL,
EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL
);
}
End of quote.
My question is: how to get the value for EfiCoreImageHandle when an EFI application was run by a boot manager, or from a UEFI shell?

Answer 1

Simply put, EfiCoreImageHandle is just a placeholder in the specification. Have a look at how I invoke OpenProtocol in the ShowEDID utility in https://github.com/fpmurphy/UEFI-Utilities-2019.
Also look at the ShowUSB utility where I currently use HandleProtocol, i.e.
Status = gBS->HandleProtocol( HandleBuffer[Index],
&gEfiUsbIoProtocolGuid,
(VOID**)&UsbIo );
I could replace the above code with:
Status = gBS->OpenProtocol( HandleBuffer[Index],
&gEfiUsbIoProtocolGuid,
(VOID **)&UsbIo,
gImageHandle,
NULL,
EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL );
Tested with UDK2018 and Lenovo T480