Making an ASCII Terminal the Console

Making an ASCII Terminal the Console

To use the kernel debugger, you must install an ASCII terminal as the system console. If you do not install an ASCII terminal as the system console, you can still use the newly built kernel under your normal configuration, but you cannot use the kernel debugger. Some systems (IRIS-4D/20, -4D/25, -4D/30, -4D/35, Indigo, Indigo2, Indy, and Crimson) allow you to use the graphics text port when the window system is not running. symmon may fail occasionally in this configuration, but it can be useful when no ASCII terminal is available.

To install an ASCII terminal as the system console:

Connect the terminal to Serial Port 1 for a single processor (or to the appropriate port number for multiprocessor systems).
Shut the system down in an orderly fashion.
Select the Command Monitor mode from the Bootstrap menu.
Type the following from the Command Monitor mode:
setenv console d
init

At this point, all console input and output occur on the ASCII terminal. Boot the system as usual. The kernel loads and, because the kernel includes the module idbg(), symmon() loads automatically from the root disk volume header partition for those systems where it is not part of the PROM.

Note: Although kernel output normally appears in a graphics window once graphics are started, the debugger still uses the ASCII terminal. The interactive version of symmon, called idbg, uses the same commands as symmon but does not stop the system from processing and does not require an ASCII terminal. You can use idbg to look at variables but not to set them. (See "Using symmon's Kernel Print Command".)