Intel Extensible Firmware Interface - Manual (Page 399)

Protocols — Bootable Image Support
Version 1.10 12/01/02 11-39
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 the DISK_IO protocol description.
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.