Console and outputs

Coreboot has various possible consoles:

Output name	direction (from the target coreboot machine point of view)	software compatibility (compatibility with software loaded after coreboot, like OS payloads etc...)
Serial console	input output	seabios grub as a payload grub running after seabios libpayload linux kernel (loaded after the payload) most GNU/Linux init systems(sysvinit, systemd, upstart etc...)
Console Over EHCI debug port	input? output
Console trough spkmodem	output only	For writting to it: coreboot's console grub's console For reading it: coreboot's/grub's spkmodem_recv uttilty (same uttility, but it's available in both git repositories)
Network console	output
Cbmem console	output only	For writting to the buffer: coreboot console output grub console output For reading the buffer: grub with the cbmemc command coreboot's userspace cbmem -c uttility

Other output:

• POST Card
• Tracing the Flash chip's access?