Intel Extensible Firmware Interface, Specification

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Extensible Firmware Interface Specification
174 12/12/00 Version 1.02
Parameters
Revision
The revision to which the block IO interface adheres. All future
revisions must be backwards compatible. If a future version is
not back wards compatible it is not the same GUID.
Media
A pointer to the
EFI_BLOCK_IO_MEDIA
data for this device.
Type
EFI_BLOCK_IO_MEDIA
is defined in “Related
Definitions”.
Reset
Resets the block device hardware. See Section 8.1.1.
ReadBlocks
Reads the requested number of blocks from the device. See
Section 8.1.2.
WriteBlocks
Writes the requested number of blocks to the device. See
Section 8.1.3.
FlushBlocks
Flushes and cache blocks. This function is optional and only
needs to be supported on block devices that cache writes. See
Section 8.1.4.
The following data values in
EFI_BLOCK_IO_MEDIA
are read-only and are updated by the
code that produces the
EFI_BLOCK_IO
protocol functions:
MediaId
The current media id. If the media changes, this value is
changed
.
RemovableMedia TRUE
if the media is removable; otherwise,
FALSE
.
MediaPresent
TRUE
if there is a media currently present in the device;
otherwise,
FALSE
. This field shows the media present status as
of the most recent
ReadBlocks()
or
WriteBlocks()
call.
LogicalPartition TRUE
if LBA 0 is the first block of a partition; otherwise
FALSE
. For media with only one partition this would be
TRUE
.
ReadOnly TRUE
if the media is marked read-only otherwise,
FALSE
. This
field shows the read-only status as of the most recent
WriteBlocks()
call.
WriteCaching TRUE
if the
WriteBlock()
function caches write data.
BlockSize
The intrinsic block size of the device. If the media changes, then
this field is updated.
IoAlign
Supplies the alignment requirement for any buffer to read or
write block(s).
LastBlock
The last logical block address on the device. If the media
changes, then this field is updated.