Extensible Firmware Interface Specification
184 12/12/00 Version 1.02
Description
The EFI_DISK_IO protocol is used to control block I/O interfaces.
The disk I/O functions allow I/O operations that need not be on the underlying device’s block
boundaries or alignment requirements. This is done by copying the data to/from internal buffers as
needed to provide the proper requests to the block I/O device. Outstanding write buffer data is
flushed by using the Flush() function of the EFI_BLOCK_IO protocol on the device handle.
The firmware automatically adds a EFI_DISK_IO interface to any EFI_BLOCK_IO interface
that is produced. It also adds file system, or logical block I/O, interfaces to any EFI_DISK_IO
interface that contains any recognized file system or logical block I/O devices. The required
formats that the firmware must automatically support are:
• The EFI FAT12, FAT16, and FAT32 file system type.
• The legacy master boot record partition block. (The presence of this on any block I/O device is
optional, but if it is present the firmware is responsible for allocating a logical device for each
partition).
• The extended partition record partition block.
• The El Torito logical block devices.
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