Intel Extensible Firmware Interface, Specification

Page: 203 / 494

Disk I/O Protocol
Version 1.02 12/12/00 185
9.1.1 EFI_DISK_IO.ReadDisk()
Summary
Reads a specified number of bytes from a device.
Prototype
EFI_STATUS
(EFIAPI *EFI_DISK_READ) (
IN EFI_DISK_IO *This,
IN UINT32 MediaId,
IN UINT64 Offset,
IN UINTN BufferSize,
OUT VOID *Buffer
);
Parameters
This
Indicates a pointer to the calling context. Type
EFI_DISK_IO
is
defined in Section 9.1.
MediaId
Id of the medium to be read.
Offset
The starting byte offset on the logical block I/O device to read from.
BufferSize
The size in bytes of
Buffer
. The number of bytes to read from the
device.
Buffer
A pointer to the destination buffer for the data. The caller is responsible
for either having implicit or explicit ownership of the buffer.
Description
The
ReadDisk()
function reads the number of bytes specified by
BufferSize
from the
device. All the bytes are read, or an error is returned. If there is no medium in the device, the
function returns
EFI_NO_MEDIA
. If the
MediaId
is not the id of the medium currently in the
device, the function returns
EFI_MEDIA_CHANGED
.
Status Codes Returned
EFI_SUCCESS The data was read correctly from the device.
EFI_DEVICE_ERROR The device reported an error while performing the read operation.
EFI_NO_MEDIA There is no medium in the device.
EFI_MEDIA_CHANGED
The MediaId is not for the current medium.
EFI_INVALID_PARAMETER The read request contains device addresses that are not valid for the
device.