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From:   Stephen Kitt <steve@sk2.org>
To:     Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org
Cc:     Theodore Ts'o <tytso@mit.edu>, linux-kernel@vger.kernel.org,
        Stephen Kitt <steve@sk2.org>
Subject: [PATCH] docs: sysctl/kernel: document random
Date:   Tue, 23 Jun 2020 13:25:14 +0200
Message-Id: <20200623112514.10650-1-steve@sk2.org>
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Sender: linux-kernel-owner@vger.kernel.org
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This documents the random directory, based on the behaviour seen in
drivers/char/random.c.

Signed-off-by: Stephen Kitt <steve@sk2.org>
---
 Documentation/admin-guide/sysctl/kernel.rst | 32 +++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 6d96f17b74a4..5f432f51f23e 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -996,6 +996,38 @@ pty
 See Documentation/filesystems/devpts.rst.
 
 
+random
+======
+
+This is a directory, with the following entries:
+
+* ``boot_id``: a UUID generated the first time this is retrieved, and
+  unvarying after that;
+
+* ``entropy_avail``: the pool's entropy count, in bits;
+
+* ``poolsize``: the entropy pool size, in bits;
+
+* ``urandom_min_reseed_secs``: obsolete (used to determine the minimum
+  number of seconds between urandom pool reseeding).
+
+* ``uuid``: a UUID generated every time this is retrieved (this can
+  thus be used to generate UUIDs at will);
+
+* ``write_wakeup_threshold``: when the entropy count drops below this
+  (as a number of bits), processes waiting to write to ``/dev/random``
+  are woken up.
+
+If ``drivers/char/random.c`` is built with ``ADD_INTERRUPT_BENCH``
+defined, these additional entries are present:
+
+* ``add_interrupt_avg_cycles``: the average number of cycles between
+  interrupts used to feed the pool;
+
+* ``add_interrupt_avg_deviation``: the standard deviation seen on the
+  number of cycles between interrupts used to feed the pool.
+
+
 randomize_va_space
 ==================
 

base-commit: 46e906144c3f4b0a7b6dcc7713fafad65b1859e0
-- 
2.20.1