升級dpdk-stable-20.11.1版本發現，原來默認make方式構建已經沒有了；變成了meson & ninja組合，試了一下，構建速度提升了不少；
meson build && ninja -C build
// sudo ninja -C build install
趕緊去學習下吧， 后面試着把那些又臭又長的Makefile或者CMakeLists.txt替換掉吧，簡單看了下manual，感覺和cmake差不多，為啥快也沒了解。先學習下傍身！
demo例子就兩行，很簡潔：
project('tutorial', 'c') # C語言工程
executable('demo', 'main.c') # target為demo 依賴 main.c
官網手冊在這里：
https://mesonbuild.com/Reference-manual.html
大概掃了下，感覺比較詳細；看了下 DPDK 的 meson.build 比看makefile舒坦多了，整個才100+ line； 即使你不完全明白是啥， 根據cmake也猜出來差不多，關鍵是個人體驗真的變快了。下面把 DPDK 的構建系統說下吧。DPDK下載的是LTS版本（DPDK 20.11.1 (LTS) http://core.dpdk.org/download/ ）
meson_options.txt (like default_options in project(), they only have effect when Meson is run for the first time, and command line arguments override any default options in build files)
get_compiler(language): returns an object describing a compiler, takes one positional argument which is the language to use
例如獲取C compiler：cc = meson.get_compiler('c')
This object is returned by configuration_data() and encapsulates configuration values to be used for generating configuration files。
eg：dpdk_conf = configuration_data() # 用於生成配置文件，支撐一些method，參考描述： configuration data object
host_machine objec
eg： 判斷編譯機體系結構： if host_machine.cpu_family().startswith('x86')
[host_machine] system = 'windows' cpu_family = 'x86' cpu = 'i686' endian = 'little'
大概長這樣子，主要是為了交叉編譯環境使用。
include_directories (since 0.38.0): specifies extra directories for header searches. # 這個和cmake 一樣了
eg：
global_inc = include_directories('.', 'config',
'lib/librte_eal/include',
'lib/librte_eal/@0@/include'.format(host_machine.system()), # 注意這里，@0@ .format(XX)還沒看哪里說明的語法，先記着雜用就行了
'lib/librte_eal/@0@/include'.format(arch_subdir),
)
subdir() # 描述同camke 構建子目錄
void subdir(dir_name, ...)
Enters the specified subdirectory and executes the meson.build file in it.
EG：
subdir('buildtools')
subdir('config')
# build libs and drivers
subdir('buildtools/pmdinfogen') # 注意上面一句 subdir('buildtools') 說明subdir只構建指定的子目錄，不會去子目錄的子目錄。
subdir('lib')
subdir('drivers')
install_subdir() # 指定subdir的 install 路徑
void install_subdir(subdir_name,
install_dir : ...,
exclude_files : ...,
exclude_directories : ...,
strip_directory : ...)
Installs the entire given subdirectory and its contents from the source tree to the location specified by the keyword argument install_dir.
eg： 指定路徑，包含的文件 和 exclude文件
subdir('examples')
install_subdir('examples',
install_dir: get_option('datadir') + '/dpdk',
exclude_files: 'meson.build')
get_option() #這個東西獲取工程可配置參數
value get_option(option_name)
Obtains the value of the project build option specified in the positional argument.
Note that the value returned for built-in options that end in dir such as bindir and libdir is always a path relative to (and inside) the prefix.
條件編譯開關形式
if get_option('enable_kmods')
subdir('kernel')
endif
# write the build config
build_cfg = 'rte_build_config.h'
configure_file(output: build_cfg,
configuration: dpdk_conf,
install_dir: join_paths(get_option('includedir'),
get_option('include_subdir_arch')))
支持 foreach
foreach lib:enabled_libs
output_message += lib + ', '
output_count += 1
if output_count == 8
output_message += '\n\t'
output_count = 0
endif
endforeach
message(output_message + '\n') 支持message打印
get_variable() # 動態獲取變量值
value get_variable(variable_name, fallback)
This function can be used to dynamically obtain a variable. res = get_variable(varname, fallback) takes the value of varname (which must be a string) and stores the variable of that name into res. If the variable does not exist, the variable fallback is stored to resinstead. If a fallback is not specified, then attempting to read a non-existing variable will cause a fatal error.
meson.build 中出現的相關函數就看完了，很好懂，和cmake語法很像， 后面再看下，編譯具體lib怎么處理庫和文件 還有編譯參數的；
隨便看一個 drivers 下面的 meson.build；掃了一眼 200行，可接受；
static_library()
buildtarget static_library(library_name, list_of_sources, ...)
Builds a static library with the given sources. Positional and keyword arguments are otherwise the same as for library, but it has one argument the others don't have:
后面在梳理吧 ~