Intel Extensible Firmware Interface, Specification

Page: 229 / 494

Load File Protocol
Version 1.02 12/12/00 211
If
BootPolicy
is
FALSE
the
FilePath
must match an exact file to be loaded. If no such file
exists,
EFI_NOT_FOUND
is returned. If
BootPolicy
is
FALSE
, and an attempt is being made
to perform a network boot through the PXE Base Code protocol,
EFI_UNSUPPORTED
is returned.
If
BootPolicy
is
TRUE
the firmware’s boot manager is attempting to load an EFI image that is a
boot selection. In this case,
FilePath
contains the file path value in the boot selection option.
Normally the firmware would implement the policy on how to handle an inexact boot file path;
however, since in this case the firmware cannot interpret the file path, the
LoadFile()
function
is responsible for implementing the policy. For example, in the case of a network boot through the
PXE Base Code protocol,
FilePath
merely points to the root of the device, and the firmware
interprets this as wanting to boot from the first valid loader. The following is list of events that
LoadFile()
will implement for a PXE boot:
•
Perform DHCP.
•
Optionally prompt the user with a menu of boot selections.
•
Discover the boot server and the boot file.
•
Download the boot file into
Buffer
and update
BufferSize
with the size of the boot file.
Status Codes Returned
EFI_SUCCESS The file was loaded.
EFI_UNSUPPORTED
The device does not support the provided BootPolicy .
EFI_INVALID_PARAMETER
FilePath is not a valid device path, or BufferSize is NULL .
EFI_NO_SUCH_MEDIA No medium was present to load the file.
EFI_DEVICE_ERROR The file was not loaded due to a device error.
EFI_NO_RESPONSE The remote system did not respond.
EFI_NOT_FOUND The file was not found.
EFI_ABORTED The file load process was manually cancelled.