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-rw-r--r--bsp-howto/getentropy.rst5
1 files changed, 4 insertions, 1 deletions
diff --git a/bsp-howto/getentropy.rst b/bsp-howto/getentropy.rst
index b460450..10303a3 100644
--- a/bsp-howto/getentropy.rst
+++ b/bsp-howto/getentropy.rst
@@ -21,7 +21,10 @@ turn are used by various cryptographic functions.
suitable for such applications.
The :c:func:`getentropy` implementation must fill the specified memory region
-of the given size with random numbers and return 0 on success.
+of the given size with random numbers and return 0 on success. A non-zero
+return may cause the :c:macro:`INTERNAL_ERROR_ARC4RANDOM_GETENTROPY_FAIL`
+internal error by one of the
+`ARC4RANDOM(3) <https://man.openbsd.org/arc4random.3>`_ functions.
In general, for embedded systems it is not easy to get some real entropy. Normally,
that can only be reached with some extra hardware support. Some microcontrollers