1 files changed, 59 insertions, 0 deletions
diff --git a/tools/testing/ktest/sample.conf b/tools/testing/ktest/sample.conf
index 87bf92a2eb99..761079edde65 100644
--- a/tools/testing/ktest/sample.conf
+++ b/tools/testing/ktest/sample.conf
@@ -73,6 +73,65 @@
 # ktest will fail to execute, and no tests will run.
 #
 
+#### Config variables ####
+#
+# This config file can also contain "config variables".
+# These are assigned with ":=" instead of the ktest option
+# assigment "=".
+#
+# The difference between ktest options and config variables
+# is that config variables can be used multiple times,
+# where each instance will override the previous instance.
+# And that they only live at time of processing this config.
+#
+# The advantage to config variables are that they can be used
+# by any option or any other config variables to define thing
+# that you may use over and over again in the options.
+#
+# For example:
+#
+# USER      := root
+# TARGET    := mybox
+# TEST_CASE := ssh ${USER}@${TARGET} /path/to/my/test
+#
+# TEST_START
+# MIN_CONFIG = config1
+# TEST = ${TEST_CASE}
+#
+# TEST_START
+# MIN_CONFIG = config2
+# TEST = ${TEST_CASE}
+#
+# TEST_CASE := ssh ${USER}@${TARGET} /path/to/my/test2
+#
+# TEST_START
+# MIN_CONFIG = config1
+# TEST = ${TEST_CASE}
+#
+# TEST_START
+# MIN_CONFIG = config2
+# TEST = ${TEST_CASE}
+#
+# TEST_DIR := /home/me/test
+#
+# BUILD_DIR = ${TEST_DIR}/linux.git
+# OUTPUT_DIR = ${TEST_DIR}/test
+#
+# Note, the config variables are evaluated immediately, thus
+# updating TARGET after TEST_CASE has been assigned does nothing
+# to TEST_CASE.
+#
+# As shown in the example, to evaluate a config variable, you
+# use the ${X} convention. Simple $X will not work.
+#
+# If the config variable does not exist, the ${X} will not
+# be evaluated. Thus:
+#
+# MAKE_CMD = PATH=/mypath:${PATH} make
+#
+# If PATH is not a config variable, then the ${PATH} in
+# the MAKE_CMD option will be evaluated by the shell when
+# the MAKE_CMD option is passed into shell processing.
 
 #### Mandatory Default Options ####