由于PC版Linux多数内核为X86或X64，而目标芯片为ARMv7，直接编译出来的版本，是无法直接用于芯片的，所以，需要配置交叉编译环境。
参考了该链接：,根据自己编译环境搭建的心得，写下此文，用来与同行人共勉！
安装交叉编译环境步骤如下：
１、安装Bazel
方法一：参考该链接： ，第3小节。
方法二：
1) sudo apt-get install openjdk-8-jdk
2) 添加Bazel源：
sudo apt-get install curl
echo "deb [arch=amd64] http://storage.googleapis.com/bazel-apt stable jdk1.8" | sudo tee /etc/apt/sources.list.d/bazel.list
curl https://bazel.build/bazel-release.pub.gpg | sudo apt-key add -
3) 安装Bazel
sudo apt-get update
sudo apt-get install bazel (安装过程中，出现googleapi网站失败问题，尝试多次几次)
4) 升级 Bazel
sudo apt-get upgrade bazel
2、设置交叉编译链
当前交叉编译SDK包目录：/home/jim/tf2arm/sysroots/x86_64-linux
在/etc/bash.bashrc最后增加如下指令：
export ARCH=arm
export PATH=/home/jim/tf2arm/sysroots/x86_64-linux/bin/:$PATH
export CROSS_COMPILE=arm-poky-linux-gnueabi-
export CC=/home/jim/tf2arm/sysroots/x86_64-linux/bin/arm-poky-linux-gnueabi-gcc
export CXX=/home/jim/tf2arm/sysroots/x86_64-linux/bin/arm-poky-linux-gnueabi-g++
export LD=/home/jim/tf2arm/sysroots/x86_64-linux/bin/arm-poky-linux-gnueabi-ld
export AR=/home/jim/tf2arm/sysroots/x86_64-linux/bin/arm-poky-linux-gnueabi-ar
export AS=/home/jim/tf2arm/sysroots/x86_64-linux/bin/arm-poky-linux-gnueabi-as
export RANLIB=/home/jim/tf2arm/sysroots/x86_64-linux/bin/arm-poky-linux-gnueabi-ranlibView Code
# 修改完成之后需要重启命令行才能生效
# 通过如下指令来确认交叉编译链是否已经设置好
echo $CC
显示/home/jim/tf2arm/sysroots/x86_64-linux/bin/arm-poky-linux-gnueabi-gcc时表示交叉编译链已经设置好
当需要更换为本机编译时屏蔽上面的指令即可
3、准备交叉编译
以下为需要新建与修改的交叉编译相关的Bazel配置脚本：
./WORKSPACE
./arm_compiler
../BUILD
../build_armv7.sh
../cross_toolchain_target_armv7.BUILD
../CROSSTOOL
3.1 修改WORKSPACE
在Tensorflow根目录下添加如下内容：
new_local_repository(
name ='toolchain_target_armv7', #交叉编译器别名
path ='/home/jim/tf2arm/sysroots/x86_64-linux', #交叉编译器路径，可根据需要自行修改
build_file = 'arm_compiler/cross_toolchain_target_armv7.BUILD' #交叉编译器描述文件
)View Code
3.2、新建交叉编译器描述文件：
新建cross_toolchain_target_armv7.BUILD：
1 major_version: "local"
2 minor_version: ""
3 default_target_cpu: "armv7"
4
5 default_toolchain {
6 cpu: "armv7"
7 toolchain_identifier: "arm-poky-linux-gnueabi"
8 }
9
10 default_toolchain {
11 cpu: "k8"
12 toolchain_identifier: "local"
13 }
14
15 toolchain {
16 abi_version: "gcc"
17 abi_libc_version: "glibc_2.23"
18 builtin_sysroot: ""
19 compiler: "compiler"
20 host_system_name: "armv7"
21 needsPic: true
22 supports_gold_linker: false
23 supports_incremental_linker: false
24 supports_fission: false
25 supports_interface_shared_objects: false
26 supports_normalizing_ar: true
27 supports_start_end_lib: false
28 supports_thin_archives: true
29 target_libc: "glibc_2.23"
30 target_cpu: "armv7"
31 target_system_name: "armv7"
32 toolchain_identifier: "arm-poky-linux-gnueabi"
33
34 tool_path { name: "ar" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-ar" }
35 tool_path { name: "compat-ld" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-ld" }
36 tool_path { name: "cpp" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-cpp" }
37 tool_path { name: "dwp" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-dwp" }
38 tool_path { name: "gcc" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc" }
39 tool_path { name: "gcov" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcov" }
40 tool_path { name: "ld" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-ld" }
41 tool_path { name: "nm" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-nm" }
42 tool_path { name: "objcopy" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-objcopy" }
43 objcopy_embed_flag: "-I"
44 objcopy_embed_flag: "binary"
45 tool_path { name: "objdump" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-objdump" }
46 tool_path { name: "strip" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-strip" }
47
48 compiler_flag: "-nostdinc"
49 compiler_flag: "-isystem"
50 compiler_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include"
51 compiler_flag: "-isystem"
52 compiler_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include"
53 compiler_flag: "-isystem"
54 compiler_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include-fixed"
55 compiler_flag: "-isystem"
56 compiler_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0"
57 compiler_flag: "-isystem"
58 compiler_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0/arm-poky-linux-gnueabi"
59
60 cxx_flag: "-isystem"
61 cxx_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include"
62 cxx_flag: "-isystem"
63 cxx_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include"
64 cxx_flag: "-isystem"
65 cxx_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include-fixed"
66 cxx_flag: "-isystem"
67 cxx_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0"
68 cxx_flag: "-isystem"
69 cxx_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0/arm-poky-linux-gnueabi"
70 cxx_flag: "-std=c++11"
71
72 cxx_builtin_include_directory: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include"
73 cxx_builtin_include_directory: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include"
74 cxx_builtin_include_directory: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include-fixed"
75 cxx_builtin_include_directory: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0"
76 cxx_builtin_include_directory: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0/arm-poky-linux-gnueabi"
77
78
79 linker_flag: "-lstdc++"
80 linker_flag: "-L/home/lyra/tf2arm/sysroots/x86_64-linux/lib"
81 linker_flag: "-L/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib"
82 linker_flag: "-L/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/lib"
83 linker_flag: "-L/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/lib"
84 linker_flag: "-Wl,--dynamic-linker=/lib/ld-linux-aarch64.so.1"
85
86 # Anticipated future default.
87 # This makes GCC and Clang do what we want when called through symlinks.
88 unfiltered_cxx_flag: "-no-canonical-prefixes"
89 linker_flag: "-no-canonical-prefixes"
90
91 # Make C++ compilation deterministic. Use linkstamping instead of these
92 # compiler symbols.
93 unfiltered_cxx_flag: "-Wno-builtin-macro-redefined"
94 unfiltered_cxx_flag: "-D__DATE__=\"redacted\""
95 unfiltered_cxx_flag: "-D__TIMESTAMP__=\"redacted\""
96 unfiltered_cxx_flag: "-D__TIME__=\"redacted\""
97
98 # Security hardening on by default.
99 # Conservative choice; -D_FORTIFY_SOURCE=2 may be unsafe in some cases.
100 # We need to undef it before redefining it as some distributions now have
101 # it enabled by default.
102 compiler_flag: "-U_FORTIFY_SOURCE"
103 compiler_flag: "-fstack-protector"
104 compiler_flag: "-fPIE"
105 linker_flag: "-pie"
106 linker_flag: "-Wl,-z,relro,-z,now"
107
108 # Enable coloring even if there's no attached terminal. Bazel removes the
109 # escape sequences if --nocolor is specified.
110 compiler_flag: "-fdiagnostics-color=always"
111
112 # All warnings are enabled. Maybe enable -Werror as well?
113 compiler_flag: "-Wall"
114 # Enable a few more warnings that aren't part of -Wall.
115 compiler_flag: "-Wunused-but-set-parameter"
116 # But disable some that are problematic.
117 compiler_flag: "-Wno-free-nonheap-object" # has false positives
118
119 # Keep stack frames for debugging, even in opt mode.
120 compiler_flag: "-fno-omit-frame-pointer"
121
122 # Stamp the binary with a unique identifier.
123 linker_flag: "-Wl,--build-id=md5"
124 linker_flag: "-Wl,--hash-style=gnu"
125
126 compilation_mode_flags {
127 mode: DBG
128 # Enable debug symbols.
129 compiler_flag: "-g"
130 }
131 compilation_mode_flags {
132 mode: OPT
133
134 # No debug symbols.
135 # Maybe we should enable https://gcc.gnu.org/wiki/DebugFission for opt or
136 # even generally? However, that can't happen here, as it requires special
137 # handling in Bazel.
138 compiler_flag: "-g0"
139
140 # Conservative choice for -O
141 # -O3 can increase binary size and even slow down the resulting binaries.
142 # Profile first and / or use FDO if you need better performance than this.
143 compiler_flag: "-O3"
144
145 # Disable assertions
146 compiler_flag: "-DNDEBUG -mcpu=cortex-a9 -mfpu=neon" #default value:cortex-a7
147 #-mcpu=cortex-m3 need compile with -mthumb
148
149 # Removal of unused code and data at link time
150 # Uncomment fllowing flag when software deploy finally
151 # compiler_flag: "-ffunction-sections"
152 # compiler_flag: "-fdata-sections"
153 # linker_flag: "-Wl,--gc-sections"
154 }
155 }
156
157
158 toolchain {
159 toolchain_identifier: "local"
160 abi_libc_version: "local"
161 abi_version: "local"
162 builtin_sysroot: ""
163 compiler: "compiler"
164 compiler_flag: "-U_FORTIFY_SOURCE"
165 compiler_flag: "-D_FORTIFY_SOURCE=2"
166 compiler_flag: "-fstack-protector"
167 compiler_flag: "-Wall"
168 compiler_flag: "-Wl,-z,-relro,-z,now"
169 compiler_flag: "-B/usr/bin"
170 compiler_flag: "-B/usr/bin"
171 compiler_flag: "-Wunused-but-set-parameter"
172 compiler_flag: "-Wno-free-nonheap-object"
173 compiler_flag: "-fno-omit-frame-pointer"
174 compiler_flag: "-isystem"
175 compiler_flag: "/usr/include"
176 cxx_builtin_include_directory: "/usr/include/c++/5.4.0"
177 cxx_builtin_include_directory: "/usr/include/c++/5"
178 cxx_builtin_include_directory: "/usr/lib/gcc/x86_64-linux-gnu/5/include"
179 cxx_builtin_include_directory: "/usr/include/x86_64-linux-gnu/c++/5.4.0"
180 cxx_builtin_include_directory: "/usr/include/c++/5.4.0/backward"
181 cxx_builtin_include_directory: "/usr/lib/gcc/x86_64-linux-gnu/5.4.0/include"
182 cxx_builtin_include_directory: "/usr/local/include"
183 cxx_builtin_include_directory: "/usr/lib/gcc/x86_64-linux-gnu/5.4.0/include-fixed"
184 cxx_builtin_include_directory: "/usr/lib/gcc/x86_64-linux-gnu/5/include-fixed"
185 cxx_builtin_include_directory: "/usr/include/x86_64-linux-gnu"
186 cxx_builtin_include_directory: "/usr/include"
187 cxx_flag: "-std=c++11"
188 host_system_name: "local"
189 linker_flag: "-lstdc++"
190 linker_flag: "-lm"
191 linker_flag: "-Wl,-no-as-needed"
192 linker_flag: "-B/usr/bin"
193 linker_flag: "-B/usr/bin"
194 linker_flag: "-pass-exit-codes"
195 needsPic: true
196 objcopy_embed_flag: "-I"
197 objcopy_embed_flag: "binary"
198 supports_fission: false
199 supports_gold_linker: false
200 supports_incremental_linker: false
201 supports_interface_shared_objects: false
202 supports_normalizing_ar: false
203 supports_start_end_lib: false
204 supports_thin_archives: false
205 target_cpu: "k8"
206 target_libc: "local"
207 target_system_name: "local"
208 unfiltered_cxx_flag: "-fno-canonical-system-headers"
209 unfiltered_cxx_flag: "-Wno-builtin-macro-redefined"
210 unfiltered_cxx_flag: "-D__DATE__=\"redacted\""
211 unfiltered_cxx_flag: "-D__TIMESTAMP__=\"redacted\""
212 unfiltered_cxx_flag: "-D__TIME__=\"redacted\""
213 tool_path {name: "ar" path: "/usr/bin/ar" }
214 tool_path {name: "cpp" path: "/usr/bin/cpp" }
215 tool_path {name: "dwp" path: "/usr/bin/dwp" }
216 tool_path {name: "gcc" path: "/usr/bin/gcc" }
217 tool_path {name: "gcov" path: "/usr/bin/gcov" }
218 tool_path {name: "ld" path: "/usr/bin/ld" }
219 tool_path {name: "nm" path: "/usr/bin/nm" }
220 tool_path {name: "objcopy" path: "/usr/bin/objcopy" }
221 tool_path {name: "objdump" path: "/usr/bin/objdump" }
222 tool_path {name: "strip" path: "/usr/bin/strip" }
223
224 compilation_mode_flags {
225 mode: DBG
226 compiler_flag: "-g"
227 }
228 compilation_mode_flags {
229 mode: OPT
230 compiler_flag: "-g0"
231 compiler_flag: "-O3"
232 compiler_flag: "-DNDEBUG"
233 compiler_flag: "-ffunction-sections"
234 compiler_flag: "-fdata-sections"
235 linker_flag: "-Wl,--gc-sections"
236 }
237 linking_mode_flags { mode: DYNAMIC }
238 }View Code
https://github.com/bazelbuild/bazel/wiki/Building-with-a-custom-toolchain
3.3、新建CROSSTOOL
CROSSTOOL文件负描述交叉编译器的各种编译选项和链接选项：
1 major_version: "local"
2 minor_version: ""
3 default_target_cpu: "armv7"
4
5 default_toolchain {
6 cpu: "armv7"
7 toolchain_identifier: "arm-poky-linux-gnueabi"
8 }
9
10 default_toolchain {
11 cpu: "k8"
12 toolchain_identifier: "local"
13 }
14
15 toolchain {
16 abi_version: "gcc"
17 abi_libc_version: "glibc_2.23"
18 builtin_sysroot: ""
19 compiler: "compiler"
20 host_system_name: "armv7"
21 needsPic: true
22 supports_gold_linker: false
23 supports_incremental_linker: false
24 supports_fission: false
25 supports_interface_shared_objects: false
26 supports_normalizing_ar: true
27 supports_start_end_lib: false
28 supports_thin_archives: true
29 target_libc: "glibc_2.23"
30 target_cpu: "armv7"
31 target_system_name: "armv7"
32 toolchain_identifier: "arm-poky-linux-gnueabi"
33
34 tool_path { name: "ar" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-ar" }
35 tool_path { name: "compat-ld" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-ld" }
36 tool_path { name: "cpp" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-cpp" }
37 tool_path { name: "dwp" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-dwp" }
38 tool_path { name: "gcc" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc" }
39 tool_path { name: "gcov" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcov" }
40 tool_path { name: "ld" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-ld" }
41 tool_path { name: "nm" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-nm" }
42 tool_path { name: "objcopy" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-objcopy" }
43 objcopy_embed_flag: "-I"
44 objcopy_embed_flag: "binary"
45 tool_path { name: "objdump" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-objdump" }
46 tool_path { name: "strip" path: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-strip" }
47
48 compiler_flag: "-nostdinc"
49 compiler_flag: "-isystem"
50 compiler_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include"
51 compiler_flag: "-isystem"
52 compiler_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include"
53 compiler_flag: "-isystem"
54 compiler_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include-fixed"
55 compiler_flag: "-isystem"
56 compiler_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0"
57 compiler_flag: "-isystem"
58 compiler_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0/arm-poky-linux-gnueabi"
59
60 cxx_flag: "-isystem"
61 cxx_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include"
62 cxx_flag: "-isystem"
63 cxx_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include"
64 cxx_flag: "-isystem"
65 cxx_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include-fixed"
66 cxx_flag: "-isystem"
67 cxx_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0"
68 cxx_flag: "-isystem"
69 cxx_flag: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0/arm-poky-linux-gnueabi"
70 cxx_flag: "-std=c++11"
71
72 cxx_builtin_include_directory: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include"
73 cxx_builtin_include_directory: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include"
74 cxx_builtin_include_directory: "/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/include-fixed"
75 cxx_builtin_include_directory: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0"
76 cxx_builtin_include_directory: "/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/include/c++/5.3.0/arm-poky-linux-gnueabi"
77
78
79 linker_flag: "-lstdc++"
80 linker_flag: "-L/home/lyra/tf2arm/sysroots/x86_64-linux/lib"
81 linker_flag: "-L/home/lyra/tf2arm/sysroots/x86_64-linux/usr/lib"
82 linker_flag: "-L/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/lib"
83 linker_flag: "-L/home/lyra/tf2arm/sysroots/x86_64-linux/cortexa9hf/usr/lib"
84 linker_flag: "-Wl,--dynamic-linker=/lib/ld-linux-aarch64.so.1"
85
86 # Anticipated future default.
87 # This makes GCC and Clang do what we want when called through symlinks.
88 unfiltered_cxx_flag: "-no-canonical-prefixes"
89 linker_flag: "-no-canonical-prefixes"
90
91 # Make C++ compilation deterministic. Use linkstamping instead of these
92 # compiler symbols.
93 unfiltered_cxx_flag: "-Wno-builtin-macro-redefined"
94 unfiltered_cxx_flag: "-D__DATE__=\"redacted\""
95 unfiltered_cxx_flag: "-D__TIMESTAMP__=\"redacted\""
96 unfiltered_cxx_flag: "-D__TIME__=\"redacted\""
97
98 # Security hardening on by default.
99 # Conservative choice; -D_FORTIFY_SOURCE=2 may be unsafe in some cases.
100 # We need to undef it before redefining it as some distributions now have
101 # it enabled by default.
102 compiler_flag: "-U_FORTIFY_SOURCE"
103 compiler_flag: "-fstack-protector"
104 compiler_flag: "-fPIE"
105 linker_flag: "-pie"
106 linker_flag: "-Wl,-z,relro,-z,now"
107
108 # Enable coloring even if there's no attached terminal. Bazel removes the
109 # escape sequences if --nocolor is specified.
110 compiler_flag: "-fdiagnostics-color=always"
111
112 # All warnings are enabled. Maybe enable -Werror as well?
113 compiler_flag: "-Wall"
114 # Enable a few more warnings that aren't part of -Wall.
115 compiler_flag: "-Wunused-but-set-parameter"
116 # But disable some that are problematic.
117 compiler_flag: "-Wno-free-nonheap-object" # has false positives
118
119 # Keep stack frames for debugging, even in opt mode.
120 compiler_flag: "-fno-omit-frame-pointer"
121
122 # Stamp the binary with a unique identifier.
123 linker_flag: "-Wl,--build-id=md5"
124 linker_flag: "-Wl,--hash-style=gnu"
125
126 compilation_mode_flags {
127 mode: DBG
128 # Enable debug symbols.
129 compiler_flag: "-g"
130 }
131 compilation_mode_flags {
132 mode: OPT
133
134 # No debug symbols.
135 # Maybe we should enable https://gcc.gnu.org/wiki/DebugFission for opt or
136 # even generally? However, that can't happen here, as it requires special
137 # handling in Bazel.
138 compiler_flag: "-g0"
139
140 # Conservative choice for -O
141 # -O3 can increase binary size and even slow down the resulting binaries.
142 # Profile first and / or use FDO if you need better performance than this.
143 compiler_flag: "-O3"
144
145 # Disable assertions
146 compiler_flag: "-DNDEBUG -mcpu=cortex-a9 -mfpu=neon" #default value:cortex-a7
147 #-mcpu=cortex-m3 need compile with -mthumb
148
149 # Removal of unused code and data at link time
150 # Uncomment fllowing flag when software deploy finally
151 # compiler_flag: "-ffunction-sections"
152 # compiler_flag: "-fdata-sections"
153 # linker_flag: "-Wl,--gc-sections"
154 }
155 }
156
157
158 toolchain {
159 toolchain_identifier: "local"
160 abi_libc_version: "local"
161 abi_version: "local"
162 builtin_sysroot: ""
163 compiler: "compiler"
164 compiler_flag: "-U_FORTIFY_SOURCE"
165 compiler_flag: "-D_FORTIFY_SOURCE=2"
166 compiler_flag: "-fstack-protector"
167 compiler_flag: "-Wall"
168 compiler_flag: "-Wl,-z,-relro,-z,now"
169 compiler_flag: "-B/usr/bin"
170 compiler_flag: "-B/usr/bin"
171 compiler_flag: "-Wunused-but-set-parameter"
172 compiler_flag: "-Wno-free-nonheap-object"
173 compiler_flag: "-fno-omit-frame-pointer"
174 compiler_flag: "-isystem"
175 compiler_flag: "/usr/include"
176 cxx_builtin_include_directory: "/usr/include/c++/5.4.0"
177 cxx_builtin_include_directory: "/usr/include/c++/5"
178 cxx_builtin_include_directory: "/usr/lib/gcc/x86_64-linux-gnu/5/include"
179 cxx_builtin_include_directory: "/usr/include/x86_64-linux-gnu/c++/5.4.0"
180 cxx_builtin_include_directory: "/usr/include/c++/5.4.0/backward"
181 cxx_builtin_include_directory: "/usr/lib/gcc/x86_64-linux-gnu/5.4.0/include"
182 cxx_builtin_include_directory: "/usr/local/include"
183 cxx_builtin_include_directory: "/usr/lib/gcc/x86_64-linux-gnu/5.4.0/include-fixed"
184 cxx_builtin_include_directory: "/usr/lib/gcc/x86_64-linux-gnu/5/include-fixed"
185 cxx_builtin_include_directory: "/usr/include/x86_64-linux-gnu"
186 cxx_builtin_include_directory: "/usr/include"
187 cxx_flag: "-std=c++11"
188 host_system_name: "local"
189 linker_flag: "-lstdc++"
190 linker_flag: "-lm"
191 linker_flag: "-Wl,-no-as-needed"
192 linker_flag: "-B/usr/bin"
193 linker_flag: "-B/usr/bin"
194 linker_flag: "-pass-exit-codes"
195 needsPic: true
196 objcopy_embed_flag: "-I"
197 objcopy_embed_flag: "binary"
198 supports_fission: false
199 supports_gold_linker: false
200 supports_incremental_linker: false
201 supports_interface_shared_objects: false
202 supports_normalizing_ar: false
203 supports_start_end_lib: false
204 supports_thin_archives: false
205 target_cpu: "k8"
206 target_libc: "local"
207 target_system_name: "local"
208 unfiltered_cxx_flag: "-fno-canonical-system-headers"
209 unfiltered_cxx_flag: "-Wno-builtin-macro-redefined"
210 unfiltered_cxx_flag: "-D__DATE__=\"redacted\""
211 unfiltered_cxx_flag: "-D__TIMESTAMP__=\"redacted\""
212 unfiltered_cxx_flag: "-D__TIME__=\"redacted\""
213 tool_path {name: "ar" path: "/usr/bin/ar" }
214 tool_path {name: "cpp" path: "/usr/bin/cpp" }
215 tool_path {name: "dwp" path: "/usr/bin/dwp" }
216 tool_path {name: "gcc" path: "/usr/bin/gcc" }
217 tool_path {name: "gcov" path: "/usr/bin/gcov" }
218 tool_path {name: "ld" path: "/usr/bin/ld" }
219 tool_path {name: "nm" path: "/usr/bin/nm" }
220 tool_path {name: "objcopy" path: "/usr/bin/objcopy" }
221 tool_path {name: "objdump" path: "/usr/bin/objdump" }
222 tool_path {name: "strip" path: "/usr/bin/strip" }
223
224 compilation_mode_flags {
225 mode: DBG
226 compiler_flag: "-g"
227 }
228 compilation_mode_flags {
229 mode: OPT
230 compiler_flag: "-g0"
231 compiler_flag: "-O3"
232 compiler_flag: "-DNDEBUG"
233 compiler_flag: "-ffunction-sections"
234 compiler_flag: "-fdata-sections"
235 linker_flag: "-Wl,--gc-sections"
236 }
237 linking_mode_flags { mode: DYNAMIC }
238 }View Code
其中，有一些重要的参数，这里简单介绍一下：
default_toolchain：默认交叉编译工具链，分为本地机和目标机
cortex A8和A9都是VFPv3，而cortex A5则用上了VFPv4了。另外M4的浮点也是VFPv4
3.4、新建BUILD
1 package(default_visibility = ["//visibility:public"])
2
3 cc_toolchain_suite(
4 name = "toolchain",
5 toolchains = {
6 "armv7|compiler": ":cc-compiler-armv7",
7 "k8|compiler": ":cc-compiler-local",
8 },
9 )
10
11 filegroup(
12 name = "empty",
13 srcs = [],
14 )
15
16 filegroup(
17 name = "arm_linux_all_files",
18 srcs = [
19 "@toolchain_target_armv7//:compiler_pieces",
20 ],
21 )
22
23 cc_toolchain(
24 name = "cc-compiler-local",
25 all_files = ":empty",
26 compiler_files = ":empty",
27 cpu = "local",
28 dwp_files = ":empty",
29 dynamic_runtime_libs = [":empty"],
30 linker_files = ":empty",
31 objcopy_files = ":empty",
32 static_runtime_libs = [":empty"],
33 strip_files = ":empty",
34 supports_param_files = 1,
35 )
36
37 cc_toolchain(
38 name = "cc-compiler-armv7",
39 all_files = ":arm_linux_all_files",
40 compiler_files = ":arm_linux_all_files",
41 cpu = "armv7",
42 dwp_files = ":empty",
43 dynamic_runtime_libs = [":empty"],
44 linker_files = ":arm_linux_all_files",
45 objcopy_files = "arm_linux_all_files",
46 static_runtime_libs = [":empty"],
47 strip_files = "arm_linux_all_files",
48 supports_param_files = 1,
49 )View Code
3.5、添加nsync交叉编译支持
nsync官方交叉编译器与自带交叉编译器可能不一致，所以，需要改动nsync的编译设置。
问题：如何找到nsync的配置代码位置？
3.5.1、 ll ~/.cache/bazel 列出bazel_lyra(当前主目录)
3.5.2、 ll ~/.cache/bazel/bazel_lyra 列出各文件夹，其中包含自动生成的随机文件夹，如果包含多个，可通过时间来判断。找到最新的即可。
3.5.3、本文中随机文件夹为：7924169126bef9c95805dc831e19e9c3，进入该文件夹下/external/nsync，打开文件BUILD，添加一个新的编译器需要添加多个位置代码：
3.5.3.1、添加config_setting
config_setting(
name = "armv7",
values = {"cpu": "armeabi-v7a"},
)
config_setting(
name = "armv8",
values = {"cpu": "arm64-v8a"},
)
3.5.3.2、在NSYNC_OPTS中添加：
# Options for C build, rather then C++11 build.
NSYNC_OPTS = select({
# Select the OS include directory.
":gcc_linux_x86_32_1": ["-I" + pkg_path_name() + "/platform/linux"],
":gcc_linux_x86_64_1": ["-I" + pkg_path_name() + "/platform/linux"],
":gcc_linux_x86_64_2": ["-I" + pkg_path_name() + "/platform/linux"],
":gcc_linux_aarch64": ["-I" + pkg_path_name() + "/platform/linux"],
":gcc_linux_ppc64": ["-I" + pkg_path_name() + "/platform/linux"],
":gcc_linux_s390x": ["-I" + pkg_path_name() + "/platform/linux"],
":clang_macos_x86_64": ["-I" + pkg_path_name() + "/platform/macos"],
":freebsd": ["-I" + pkg_path_name() + "/platform/freebsd"],
":ios_x86_64": ["-I" + pkg_path_name() + "/platform/macos"],
":android_x86_32": ["-I" + pkg_path_name() + "/platform/linux"],
":android_x86_64": ["-I" + pkg_path_name() + "/platform/linux"],
":android_armeabi": ["-I" + pkg_path_name() + "/platform/linux"],
":android_arm": ["-I" + pkg_path_name() + "/platform/linux"],
":android_arm64": ["-I" + pkg_path_name() + "/platform/linux"],
":armv7": ["-I" + pkg_path_name() + "/platform/linux"],
":armv8": ["-I" + pkg_path_name() + "/platform/linux"],
":msvc_windows_x86_64": ["-I" + pkg_path_name() + "/platform/win32"],
"//conditions:default": [],
}) + select({
# Select the compiler include directory.
":gcc_linux_x86_32_1": ["-I" + pkg_path_name() + "/platform/gcc"],
":gcc_linux_x86_64_1": ["-I" + pkg_path_name() + "/platform/gcc"],
":gcc_linux_x86_64_2": ["-I" + pkg_path_name() + "/platform/gcc"],
":gcc_linux_aarch64": ["-I" + pkg_path_name() + "/platform/gcc"],
":gcc_linux_ppc64": ["-I" + pkg_path_name() + "/platform/gcc"],
":gcc_linux_s390x": ["-I" + pkg_path_name() + "/platform/gcc"],
":clang_macos_x86_64": ["-I" + pkg_path_name() + "/platform/clang"],
":freebsd": ["-I" + pkg_path_name() + "/platform/clang"],
":ios_x86_64": ["-I" + pkg_path_name() + "/platform/clang"],
":android_x86_32": ["-I" + pkg_path_name() + "/platform/gcc"],
":android_x86_64": ["-I" + pkg_path_name() + "/platform/gcc"],
":android_armeabi": ["-I" + pkg_path_name() + "/platform/gcc"],
":android_arm": ["-I" + pkg_path_name() + "/platform/gcc"],
":android_arm64": ["-I" + pkg_path_name() + "/platform/gcc"],
":armv7": ["-I" + pkg_path_name() + "/platform/gcc"],
":armv8": ["-I" + pkg_path_name() + "/platform/gcc"],
":msvc_windows_x86_64": ["-I" + pkg_path_name() + "/platform/msvc"],
}) + select({
# Apple deprecated their atomics library, yet recent versions have no
# working version of stdatomic.h; so some recent versions need one, and
# other versions prefer the other. For the moment, just ignore the
# depreaction.
":clang_macos_x86_64": ["-Wno-deprecated-declarations"],
"//conditions:default": [],
}) + NSYNC_OPTS_GENERIC
3.5.3.3、在NSYNC_SRC_PLATFORM中添加：
NSYNC_SRC_PLATFORM = select({
":gcc_linux_x86_32_1": NSYNC_SRC_LINUX,
":gcc_linux_x86_64_1": NSYNC_SRC_LINUX,
":gcc_linux_x86_64_2": NSYNC_SRC_LINUX,
":gcc_linux_aarch64": NSYNC_SRC_LINUX,
":gcc_linux_ppc64": NSYNC_SRC_LINUX,
":gcc_linux_s390x": NSYNC_SRC_LINUX,
":clang_macos_x86_64": NSYNC_SRC_MACOS,
":freebsd": NSYNC_SRC_FREEBSD,
":ios_x86_64": NSYNC_SRC_MACOS,
":android_x86_32": NSYNC_SRC_ANDROID,
":android_x86_64": NSYNC_SRC_ANDROID,
":android_armeabi": NSYNC_SRC_ANDROID,
":android_arm": NSYNC_SRC_ANDROID,
":android_arm64": NSYNC_SRC_ANDROID,
":armv7": NSYNC_SRC_LINUX,
":armv8": NSYNC_SRC_LINUX,
":msvc_windows_x86_64": NSYNC_SRC_WINDOWS,
})
3.5.3.4、在NSYNC_TEST_SRC_PLATFORM中添加：
NSYNC_TEST_SRC_PLATFORM = select({
":gcc_linux_x86_32_1": NSYNC_TEST_SRC_LINUX,
":gcc_linux_x86_64_1": NSYNC_TEST_SRC_LINUX,
":gcc_linux_x86_64_2": NSYNC_TEST_SRC_LINUX,
":gcc_linux_aarch64": NSYNC_TEST_SRC_LINUX,
":gcc_linux_ppc64": NSYNC_TEST_SRC_LINUX,
":gcc_linux_s390x": NSYNC_TEST_SRC_LINUX,
":clang_macos_x86_64": NSYNC_TEST_SRC_MACOS,
":freebsd": NSYNC_TEST_SRC_FREEBSD,
":ios_x86_64": NSYNC_TEST_SRC_MACOS,
":android_x86_32": NSYNC_TEST_SRC_ANDROID,
":android_x86_64": NSYNC_TEST_SRC_ANDROID,
":android_armeabi": NSYNC_TEST_SRC_ANDROID,
":android_arm": NSYNC_TEST_SRC_ANDROID,
":android_arm64": NSYNC_TEST_SRC_ANDROID,
":armv7": NSYNC_TEST_SRC_LINUX,
":armv8": NSYNC_TEST_SRC_LINUX,
":msvc_windows_x86_64": NSYNC_TEST_SRC_WINDOWS,
})View Code
4、运行configure配置脚本
cd tensorflow
./configure
配置过程注意选项：
4.1 python库位置
4.2 optimization flags: 默认为-march=native，交叉编译时需要修改，可根据实际芯片架构设置，如：march=armv7-a
4.3 其它选项一律选No即可
build_armv7.sh（交叉编译Tensorflow主体部分）:
bazel build --copt="-fPIC" --copt="-march=armv7-a" --cxxopt="fPIC" --cxxopt="-march=armv7-a" --verbose_failures --crosstool_top=//arm_compiler:toolchain --cpu=armv7 --config=opt tensorflow/examples/label_image/...View Code
可通过设置参数:-jobs 来指定编译线程数，如果不指定，默认采用CPU核心数x2的线程数
编译过程中可能会出现各种错误，可参考以下链接处理：
Tensorflow交叉编译错误集锦
编译完成后，会生成如下目标文件：
bazel-bin/tensorflow/libtensorflow_framework.so
bazel-bin/tensorflow/examples/label_image
6、交叉编译Tensorflow-lite
交叉编译过程参考tensorfow/contrib/lite/g3doc/rpi.md
编译之前对多线程代码进行修改，默认线程数为4，参考以下代码：
const Eigen::ThreadPoolDevice& GetThreadPoolDevice() {
const int thread_count = 4;
static Eigen::ThreadPool* tp = new Eigen::ThreadPool(thread_count);
static EigenThreadPoolWrapper* thread_pool_wrapper =
new EigenThreadPoolWrapper(tp);
static Eigen::ThreadPoolDevice* device =
new Eigen::ThreadPoolDevice(thread_pool_wrapper, thread_count);
return *device;
}
将上述代码修改为：
const Eigen::ThreadPoolDevice& GetThreadPoolDevice() {
int thread_count = 1;
const char *val = getenv("OMP_NUM_THREADS");
if (val != nullptr) {
thread_count = atoi(val);
}
static Eigen::ThreadPool* tp = new Eigen::ThreadPool(thread_count);
static EigenThreadPoolWrapper* thread_pool_wrapper =
new EigenThreadPoolWrapper(tp);
static Eigen::ThreadPoolDevice* device =
new Eigen::ThreadPoolDevice(thread_pool_wrapper, thread_count);
return *device;
}View Code
第一步:
./tensorflow/contrib/lite/download_dependencies.sh 下载依赖（成功的话，只需执行一次）
第二步：
build_imx6_lib.sh
1 set -e
2
3 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
4 cd "$SCRIPT_DIR/../../.."
5
6 CC_PREFIX=arm-poky-linux-gnueabi- make -j 3 -f tensorflow/contrib/lite/Makefile TARGET=imx6 TARGET_ARCH=armv7aView Code
第三步：
./tensorflow/contrib/lite/schema
编译成功后，会生成如下目标文件：
tensorflow/contrib/lite/gen/lib/rpi_armv7/libtensorflow-lite.a
tensorflow/contrib/lite/gen/bin/rpi_armv7/benchmark_model
7、交叉编译Tensorflow-lite的label_image测试工具
bazel build --copt="-fPIC" --copt="-march=armv7-a" --cxxopt="-fPIC" --cxxopt="-march=armv7-a" --verbose_failures --crosstool_top=//arm_compiler:toolchain --cpu=armv7 --config=opt //tensorflow/contrib/lite/examples/label_image:label_imageView Code
8、本地编译TOCO模型转换工具
TOCO转换工具与模型预测无关，建议运行在X86机器上。
为了最小化运行时环境，使用了Flatbuffer这种轻量级的数据存储格式，所以，在测试前需要使用TOCO工具进行模型转换：
bazel build tensorflow/contrib/lite/toco:toco (关闭交叉编译链选项)
完成编译后生成如下目标文件：
bazel-bin/tensorflow/contrib/lite/toco/toco （toco工具编译出来之后尽量不要移动位置，建议原地执行）
到此，Tensorflow-lite交叉编译环境搭建完成！
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