Intel Extensible Firmware Interface, Спецификация

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Extensible Firmware Interface Specification
418 12/12/00 Version 1.02
Queued CDBs
0x00
0x1F
0x40
0x5F
0x20
0x3F
CDB
Set Queue bit.
Set Link bit.
CDB
Do not set
Queue bit.
Set Link bit.
CDB
Do not set
Queue bit.
Do not set
Link bit.
Figure G-8. Queued CDBs
When a command is queued a StatFlag of
PXE_STATFLAG_COMMAND_QUEUED
is set (if linked
commands are queued only the StatFlag of the first CDB gets set). This signals that the command
was added to the queue. Commands in the queue will be run on a first-in, first-out, basis. When a
command fails, the next command in the queue is run. When a linked command in the queue fails,
execution on the list stops. The next command, or list of commands, that was added to the
command queue will be run.
G.4.2 Get State
This command is used to determine the operational state of the UNDI. An UNDI has three possible
operational states:
Stopped: A stopped UNDI is free for the taking. When all interface numbers (IFnum)
for a particular S/W UNDI are stopped, that S/W UNDI image can be relocated or
removed. A stopped UNDI will accept Get State and Start commands.
Started: A started UNDI is in use. A started UNDI will accept Get State, Stop, Get Init
Info and Initialize Commands.
Initialized: An initialized UNDI is in used. An initialized UNDI will accept all
commands except: Start, Stop and Initialize.
Drivers, NBPs and applications should not use UNDIs that are already started or initialized.
No other operational checks are made by this command. If this is a S/W UNDI, the
PXE_START_CPB.Delay()
and
PXE_START_CPB.Virt2Phys()
callbacks will not be
used.