The mismatch between the allowed characters in shell variables and
device parameters is a common pitfall, especially because device
tree node names often have hyphens in them, which is disallowed by
hush.
While such variables can be read by the ${variable-example}, setting
them is only possible with the setenv command. Reflect this in the
documentation.
Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
---
Cc: Matthias Fend <Matthias.Fend@xxxxxxxxxxxxxx>
---
Documentation/user/driver-model.rst | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/Documentation/user/driver-model.rst b/Documentation/user/driver-model.rst
index a0fd3e99b55b..c543d6d9c410 100644
--- a/Documentation/user/driver-model.rst
+++ b/Documentation/user/driver-model.rst
@@ -88,7 +88,14 @@ The parameters can be used as shell variables:
.. code-block:: sh
eth0.ipaddr=192.168.23.15
- echo "my current ip is: $eth0.ipaddr"
+ echo "my current ip is: ${eth0.ipaddr}"
+
+.. note::
+
+ Hush shell syntax for defining and setting variables is the same, so
+ some characters such as hyphens are not allowed on the left hand side
+ of a shell variable assignment. :ref:`command_setenv`, if enabled,
+ can still be used to write such a variable though.
device variables may have a type, so assigning wrong values may fail:
--
2.28.0
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