doc: add BPF library guide

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>

MAINTAINERS

@@ -1105,6 +1105,7 @@ M: Konstantin Ananyev <konstantin.ananyev@intel.com>
 F: lib/librte_bpf/
 F: test/bpf/
 F: test/test/test_bpf.c
+F: doc/guides/prog_guide/bpf_lib.rst
 
 
 Test Applications

doc/guides/prog_guide/bpf_lib.rst

@@ -0,0 +1,38 @@
+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright(c) 2018 Intel Corporation.
+
+Berkeley Packet Filter Library
+==============================
+
+The DPDK provides an BPF library that gives the ability
+to load and execute Enhanced Berkeley Packet Filter (eBPF) bytecode within
+user-space dpdk application.
+
+It supports basic set of features from eBPF spec.
+Please refer to the
+`eBPF spec <https://www.kernel.org/doc/Documentation/networking/filter.txt>`
+for more information.
+Also it introduces basic framework to load/unload BPF-based filters
+on eth devices (right now only via SW RX/TX callbacks).
+
+The library API provides the following basic operations:
+
+*  Create a new BPF execution context and load user provided eBPF code into it.
+
+*   Destroy an BPF execution context and its runtime structures and free the associated memory.
+
+*   Execute eBPF bytecode associated with provided input parameter.
+
+*   Provide information about natively compiled code for given BPF context.
+
+*   Load BPF program from the ELF file and install callback to execute it on given ethdev port/queue.
+
+Not currently supported eBPF features
+-------------------------------------
+
+ - JIT for non X86_64 platforms
+ - cBPF
+ - tail-pointer call
+ - eBPF MAP
+ - skb
+ - external function calls for 32-bit platforms

doc/guides/prog_guide/index.rst

@@ -53,6 +53,7 @@ Programmer's Guide
     vhost_lib
     metrics_lib
     port_hotplug_framework
+    bpf_lib
     source_org
     dev_kit_build_system
     dev_kit_root_make_help