Configuration Software and Utilities
101
Console Redirection
The BIOS supports redirection of video output and keyboard input via serial link. This section
details the serial redirection scheme. For redirection over LAN (Serial over LAN or SOL), see
the ISM online help.
When console redirection is enabled, local (host server) keyboard input and video output are
passed both to the local keyboard and video connections, and to the remote console via the
serial link. Keyboard inputs from both sources are considered valid and video is displayed to
both outputs.
With console redirection, you can operate the server system without having a keyboard or
monitor attached to it. Setup and any other text-based utilities can be accessed via console
redirection. Note that serial redirection uses PC-ANSI and the UART settings assume 1 stop
bit.
Operation
NOTE
When console redirection is enabled, the text on the local console screen will
draw slowly when it is operating under EFI. This is especially true when a low
baud-rate modem is used, such as the default baud rate of 19.2K. This is because
EFI is not an interrupt-driven environment and it uses a polling mechanism to
communicate with the remote console.
When redirecting through a modem, as opposed to a null modem cable, the modem needs to be
configured as follows:
•
Auto-answer (for example,
ATS0=2
, to answer after two rings).
•
Modem reaction to DTR set to return to command state (such as
AT&D1
). Failure to
provide the modem reaction results in the modem either dropping the link when the server
reboots (as in
AT&D0
) or becoming unresponsive to server baud rate changes (as in
AT&D2
).
•
The Setup/EMP option for handshaking must be set to
CTS/RTS + CD
for optimum
performance. The CD refers to carrier detect. If the EMP is sharing the COM port with
serial redirection, the handshaking must be set to
CTS/RTS+ CD
. In selecting this form of
handshaking, the server is prevented from sending video updates to a modem that is not
connected to a remote modem. If this is not selected, video update data being sent to the
modem inhibits many modems from answering an incoming call. An EMP option utilizing
CD should not be used if a modem is not used and the CD is not connected.
Once console redirection is selected via Setup, redirection binary is loaded into memory and
activated during POST. While redirection cannot be removed without rebooting, it can be
inhibited and restarted.
Inhibiting and restarting is accomplished through an INT 16h mechanism. The standard INT
16h (keyboard handler) function ah=05h places a keystroke in the key buffer, as if an actual key
is pressed. Keystrokes buffered this way are examined by redirection; if a valid command
string has been sent, it is executed. The following commands are supported:
•
Esc-CDZ0
- Inhibit Console Redirection. In order to inhibit redirection, the software must
call INT 16h, function ah=05h five times to place the five keys in the key buffer.
Keystrokes sent to the INT 16h buffers to invoking a command are buffered, and should be
removed through normal INT 16h calls to prevent these keystrokes from being passed to
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