[PATCH v8,4/4] Documentation/admin-guide/module-signing.rst: add openssl command option example for CodeSign EKU

[Lee, Chun-Yi]

Add an openssl command option example for generating CodeSign extended
key usage in X.509 when CONFIG_CHECK_CODESIGN_EKU is enabled.

Signed-off-by: "Lee, Chun-Yi" <jlee@xxxxxxxx>
---
 Documentation/admin-guide/module-signing.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/admin-guide/module-signing.rst b/Documentation/admin-guide/module-signing.rst
index 7d7c7c8a545c..ca3b8f19466c 100644
--- a/Documentation/admin-guide/module-signing.rst
+++ b/Documentation/admin-guide/module-signing.rst
@@ -170,6 +170,12 @@ generate the public/private key files::
 	   -config x509.genkey -outform PEM -out kernel_key.pem \
 	   -keyout kernel_key.pem
 
+When ``CONFIG_CHECK_CODESIGN_EKU`` option is enabled, the following openssl
+command option should be added where for generating CodeSign extended key usage
+in X.509::
+
+        -addext "extendedKeyUsage=codeSigning"
+
 The full pathname for the resulting kernel_key.pem file can then be specified
 in the ``CONFIG_MODULE_SIG_KEY`` option, and the certificate and key therein will
 be used instead of an autogenerated keypair.
-- 
2.16.4