[rtems-docs commit] Clarify INTERNAL_ERROR_ARC4RANDOM_GETENTROPY_FAIL

[Sebastian Huber]

Module:    rtems-docs
Branch:    master
Commit:    70f23e475b23af25e2035e2b5cfe1f5a8a7ea9f9
Changeset: http://git.rtems.org/rtems-docs/commit/?id=70f23e475b23af25e2035e2b5cfe1f5a8a7ea9f9

Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
Date:      Mon Nov 20 08:08:30 2017 +0100

Clarify INTERNAL_ERROR_ARC4RANDOM_GETENTROPY_FAIL

Update #3239.

---

 bsp-howto/getentropy.rst | 5 ++++-
 c-user/fatal_error.rst   | 3 ++-
 2 files changed, 6 insertions(+), 2 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
diff --git a/c-user/fatal_error.rst b/c-user/fatal_error.rst
index 396cb44..320227b 100644
--- a/c-user/fatal_error.rst
+++ b/c-user/fatal_error.rst
@@ -390,7 +390,8 @@ INTERNAL_ERROR_ILLEGAL_USE_OF_FLOATING_POINT_UNIT (38)
 
 INTERNAL_ERROR_ARC4RANDOM_GETENTROPY_FAIL (39)
     A :c:func:`getentropy` system call failed in one of the `ARC4RANDOM(3)
-    <https://man.openbsd.org/arc4random.3>`_ functions.
+    <https://man.openbsd.org/arc4random.3>`_ functions.  This fatal error can
+    only be fixed with a different implementation of :c:func:`getentropy`.
 
 Operations
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