[coreboot] Understanding BIOS I/O Adresses

Alexander Couzens lynxis at fe80.eu
Mon Nov 16 04:12:04 CET 2015

Hi panic,

0x80 is a debug io port. There are pci cards showing you one byte on a
lcd display.
coreboot is using 0x80 too for debug output. The interface is simple,
the firmware/bios will increment the value sent to that address while
it's booting. In the case your bios is hangs somewhere while booting,
you can read from the card it's last byte sent to that ioport 0x80.

No idea what for the others io codes are.

Alexander Couzens

mail: lynxis at fe80.eu
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