Change in coreboot[master]: console: Allow configuring log level through CBFS

[Patrick Georgi (Code Review)]

Attention is currently required from: Marc Jones, Julius Werner, Patrick Rudolph.
Hello build bot (Jenkins), Greg Edelston, Jakub Czapiga, Paul Menzel, Julius Werner, Angel Pons, Dossym Nurmukhanov,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/45208

to look at the new patch set (#17).

Change subject: console: Allow configuring log level through CBFS
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console: Allow configuring log level through CBFS

Allow configuring loglevel through CBFS in addition to the compile
time default and the (not always available) "CMOS" nvram.

In the first stage (usually bootblock), only the compile time default
is used (no change to previous behavior)

Later stages first look for valid configuration in nvram, then in
CBFS and finally use the compile time default: The first usable value
is chosen.

"Fast" consoles still log at BIOS_DEBUG level or slow console loglevel,
whatever is more verbose.

With this change a single image can be used both for deployment and
testing scenarios with only a dedicated CBFS file modified to toggle
(the typically slow) serial console.

BUG=b:151346403
BRANCH=none
TEST=Taking a Chrome OS config for google/hatch, it behaves as
expected with no entry present and both entry states with negligible
performance loss.

Change-Id: I4f1f5c45e5ea889176d04e0db438ca2aa7c536ee
Signed-off-by: Patrick Georgi 
---
M src/console/init.c
M tests/console/Makefile.inc
2 files changed, 19 insertions(+), 3 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/08/45208/17