From d37de3c41de46ebda801d60b171875352267977d Mon Sep 17 00:00:00 2001
From: Senthil Kumaran <senthil@uthcode.com>
Date: Sat, 18 Jun 2016 11:21:50 -0700
Subject: [PATCH] issue27021 - Document SC_IOV_MAX limitation imposed by OS on
 os.writev.
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Patch contributed Марк Коренберг.
---
 Doc/library/os.rst | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 743efb691a2..7b26953ade5 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -1195,7 +1195,11 @@ or `the MSDN <https://msdn.microsoft.com/en-us/library/z0kc8e3z.aspx>`_ on Windo
 .. function:: writev(fd, buffers)
 
    Write the contents of *buffers* to file descriptor *fd*. *buffers* must be a
-   sequence of :term:`bytes-like objects <bytes-like object>`.
+   sequence of :term:`bytes-like objects <bytes-like object>`. Buffers are
+   processed in array order. Entire contents of first buffer is written before
+   proceeding to second, and so on. The operating system may set a limit
+   (sysconf() value SC_IOV_MAX) on the number of buffers that can be used.
+
    :func:`~os.writev` writes the contents of each object to the file descriptor
    and returns the total number of bytes written.