board-status: Add README

It explains the prerequisites to run the script, some
background on how to setup the computer running the script,
and the board it gathers the information from.

That information is too long to fit inside the script's
help.

Change-Id: Iecba7310ff1583149c02728e955716775bcbbdc4
Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>
Reviewed-on: https://review.coreboot.org/6660
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

util/board_status/README

@@ -0,0 +1,50 @@
+General information on boot logs
+================================
+To gather good boot logs, you must set the debug level to Spew.
+
+If your board uses CMOS configuration[1], you can do it like this:
+nvramtool -w debug_level=Spew
+
+Else you will need to have to set the default log level at compile
+time, to do that go in "Console  --->" in make menuconfig, then set
+"Default console log level" to SPEW
+
+Rereference:
+------------
+[1] in make menuconfig you should have: [*] Use CMOS for configuration values
+    This option is also known as CONFIG_USE_OPTION_TABLE in Kconfig.
+Information trough SSH
+======================
+board_status.sh can gather information trough ssh with the -r
+option.
+
+When using "-r <host>", The script will attempt to log into
+root@<host>.
+In order for "-r <host>" to work, the script has to be able
+to log into the remote host's root account, without having
+to provide a password.
+That can be achieved with the use of SSH keys and ssh-agent.
+
+board_status.sh expects the remote host to have the following
+programs in its path: cbmem, dmesg
+
+Boot log gathering trough a serial port
+=======================================
+When using -s </dev/xxx>, board_status.sh starts by retrieving the
+boot log trough the serial port.
+
+To produce such logs, power off the board, run board_status.sh
+with the right arguments, power on the board.
+At that point the logs will be displayed by board_status.sh as they
+are produced by the board.
+
+Enter will have to be pressed once the board has booted and is in a
+state where the script is able to log into that board.
+
+Publishing
+==========
+The -u switch will publish the results: It will make a git patch out
+of the status information, that will be directly pushed in the
+board-status repository.
+It expects the user to already have an account in coreboot's gerrit
+instance.