Console and outputs

From coreboot
Revision as of 12:52, 15 December 2013 by GNUtoo (talk | contribs)
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The wiki is being retired!

Documentation is now handled by the same processes we use for code: Add something to the Documentation/ directory in the coreboot repo, and it will be rendered to https://doc.coreboot.org/. Contributions welcome!

Coreboot has various possible consoles:

Output name direction (from the target coreboot machine point of view) Hardware requirements software compatibility (compatibility with software loaded after coreboot, like OS payloads etc...)
Serial console

(sends coreboot logs over the serial port)

  • input
  • output
  • An internal(not USB) serial port:
    • it can on the mainboard
    • it can also be a PCIe OXPCIe952 card with the 0x1415 and 0xc158 vendor and device ID (respectively).
    • USB serial ports are not supported by coreboot yet.
  • 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

(sends coreboot logs over the usb debug port)

  • input?
  • output
  • grub
  • linux kernel in its early initialisation (I'm not sure that it can be kept afterward, because, after the early initialisation, by default it tries to initialise the USB port normally)
Console trough spkmodem

(sends coreboot logs over the sound card)

  • output only

For writting to it from the coreboot target computer:

  • coreboot's console
  • grub's console

For reading it from a remote computer:

  • coreboot's/grub's spkmodem_recv uttilty (same uttility, but it's available in both git repositories)
Network console

(sends coreboot logs over the network)

  • output
  • probably no input
Cbmem console

(Ram buffer, like dmesg)

  • output only for coreboot.
  • input/output for grub.
  • It requires the computer to be booted to retrive the logs.

For writting to the buffer which is in the coreboot target computer:

  • coreboot console output
  • grub console output
  • seabios

For reading the buffer on the coreboot target computer, after coreboot booted:

  • grub with the cbmemc command
  • coreboot's userspace cbmem -c uttility

Other output: