haiku/docs/develop/kernel/arch/sparc/openboot.txt
Adrien Destugues 506f9764d4 Some notes about openboot.
As I keep looking for the commands to do anything...

Next step is to figure out network booting and set up an easy way to
test haiku_loader.
2019-05-19 14:31:21 +02:00

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Openboot is Sun's implementation of Open Firmware. So we should be able to share
a lot of code with the PowerPC port. There are some differences however.
Executable format
=================
PowerPC uses COFF. Sparc uses a.out, which is a lot simpler. According to the
spec, some fields should be zeroed out, but they say implementation may chose
to allow other values, so it's possible a standard a.out file would work as
well.
Openfirmware prompt
===================
To get the prompt on display, use STOP+A at boot until you get the "ok" prompt.
On some machines, if no keyboard is detected, the ROM will assume it is set up
in headless mode, and will expect a BREAK+A on the serial port.
STOP+N resets all variables to default values (in case you messed up input or
output, for example).
Useful commands
===============
Disable autoboot to get to the openboot prompt and stop there
-------------------------------------------------------------
setenv auto-boot? false
Configuring for keyboard/framebuffer io
---------------------------------------
setenv screen-#columns 160
setenv screen-#rows 49
setenv output-device screen:r1920x1080x60
setenv input-device keyboard
Configuring openboot for serial port
------------------------------------
setenv ttya-mode 38400,8,n,1,-
setenv output-device ttya
setenv input-device ttya
reset
Boot from network
-----------------
rarp:
boot net
dhcp:
boot net:dhcp