Cbmem console

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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!

Howto

Coreboot configuration

If your hardware supports early cbmem console you should see the following in "Console --->" after making make menuconfig

[*] Send console output to a CBMEM buffer
(0x10000) Room allocated for console output in CBMEM
(0xc00) Room allocated for console output in Cache as RAM

Else you may try to select the following configuration option in "General setup --->"

[*] The CBMEM space is dynamically grown.
Note that it can fails to compile if that is not supported either for your device.
Then select Send console output to a CBMEM buffer like explained before.

Runtime

  • coreboot's cbmem uttility(in util/cbmem) can read that buffer:
sudo cbmem -c
  • grub from bzr is also able to read the cbmem buffer.

Disavantages

  • require a booted computer
  • Logs are often incomplete: part of the logs are replaced with:
*** Log truncated, 348 characters dropped. ***