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Rolling BIOS
With the Rolling BIOS feature, two copies of the BIOS are stored on the main board. These are
designated as the primary and secondary BIOS image. The primary image is the BIOS in use. The
BIOS normally boots to this primary image.
BIOS updates are diverted to the secondary image. During the subsequent boot following the BIOS
update, the system will continue to attempt to boot from the primary BIOS image. After
determining that a BIOS update occurred, the system will attempt to boot the new BIOS. If the new
BIOS fails to boot, specialized hardware switches the boot back to the known good BIOS image.
The BIOS will log the boot failure event to the SEL and display a POST error message.
Console Redirection
The BIOS supports redirection of both video and keyboard through a serial link (COM port). 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, the system can be operated without a host keyboard or monitor attached to the system
and run entirely via the remote console. Setup and any other text-based utilities can be accessed via
console redirection.
Serial Configuration Settings
When redirecting through a modem (as opposed to a null modem cable), the modem needs to be
configured with the following:
Auto-answer (for example, ATS0=2, to answer after two rings).
Modem reaction to DTR set to return to command state (e.g., AT&D1).
Either failure to provide the second item will result in the modem dropping the link when the server
reboots (as in AT&D0) or becoming unresponsive to server baud rate changes (as in AT&D2).
The option for handshaking must be set to RTS/CTS + CD for optimum performance. The CD
refers to carrier detect. If EMP is sharing the COM port with serial redirection, the handshaking
must be set to Xon/Xoff + 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.
Both EMP and console redirection require N, 8, 1 mode (no parity, 8-bit data, 1 stop bit).
The BIOS does not require that the splash logo be turned off for console redirection to function.
The BIOS supports multiple consoles, some of which are in graphics mode and some in text mode.
The graphics consoles can display the logo while the text consoles receive the redirected text.
The console redirection ends at the beginning of the Legacy OS boot (INT 19h).
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Troubleshooting
