如何在 Ubuntu 上用 Yocto 创建你自己的 Linux 发行版
========================================

### 本文内容

本文主要聚焦在如何使用 Yocto 在 Ubuntu 上创建一个最小化的 Linux 发行版。Yocto 项目在嵌入式 Linux 的世界非常著名，这是因为它用起来非常灵活、方便。Yocto 的目标是为嵌入式软硬件开发商创建自己的 Linux 发行版。本文我们将会创建一个可以运行在 QEMU 上的最小化的 Linux，并且在 QEMU 上实际运行。

### 开发机的基本条件

*  最少 4-6 GB 内存
*  最新版的 Ubuntu 系统（本文使用了 16.04 LTS）
*  磁盘剩余空间至少 60-80 GB
*  在创建 Linux 发行版之前先安装下面的软件包
*  下载最新的 Yocto（Poky 是其最小开发环境）稳定分支

```
apt-get update
```
```
apt-get install wget git-core unzip make gcc g++ build-essential subversion sed autoconf automake texi2html texinfo coreutils diffstat python-pysqlite2 docbook-utils libsdl1.2-dev libxml-parser-perl libgl1-mesa-dev libglu1-mesa-dev xsltproc desktop-file-utils chrpath groff libtool xterm gawk fop
```

![Install prerequisites for Yocto](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/1-pre_requisite_packages-1.png)

如下所示，开发环境要安装的软件包将近 1GB 大小。

 ![Install the development packages](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/2-pre_requisite_packages-2.png)

在这个教程中，系统上克隆的是 poky 的 `morty` 稳定分支。

```
 git clone -b morty git://git.yoctoproject.org/poky.git
```

![install poky](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/download_morty_of_yocto.png)

进入 `poky` 目录，然后运行下面的命令为 Yocto 开发环境设置（设置/导出）一些环境变量。

```
source oe-init-build-env
```

如下所示，在运行了 open embedded (oe) 的构建环境脚本之后，终端里的路径会自动切换到 `build` 目录，以便进行之后行发行版的的配置和构建。

 ![Prepare OE build environment](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/source_environment_script.png)

上面的截屏展示了在 `conf` 目录下创建的文件 `local.conf`。这是 Yocto 用来设置目标机器细节和 SDK 的目标架构的配置文件。

如下所示，这里设置的目标机器是 `qemux86-64`。

 ![Set the target machine type](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/selected_target.png)

如下面截图所示，在 `local.conf` 中取消下面参数的注释符号。

```
DL_DIR ?= "${TOPDIR}/downloads"
```

![Configure local.conf file](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/uncheck_Download_parameters.png)

```
SSTATE_DIR ?= "${TOPDIR}/sstate-cache"
```

![Set SSTATE_DIR](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/uncheck_sstate_parametes.png)

```
TMPDIR ?= "${TOPDIR}/tmp"
```

![Set TMPDIR](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/tempdir_uncheck_paramerter.png)

```
PACKAGE_CLASSES ?= "package_rpm"
SDKMACHINE ?= "i686"
```

![Set PACKAGE_CLASSES and SDKMACHINE](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/sdk_and_package_selection.png)

如下所示，在 `local.conf` 中为基于 Yocto 的 Linux 设置空密码和后续的一些参数。否则的话用户就不能登录进新的发行版。

```
EXTRA_IMAGE_FEATURES ?= "debug-tweaks"
```

![Set debug-tweaks option](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/extra-features_for_blank_password.png)

我们并不准备使用任何图形化工具来创建 Linux OS，比如 `toaster` （`hob` 已经不再支持了）。

### Yocto 编译构建过程

现在运行下面的 `bitbake` 工具命令开始为选定的目标机器下载和编译软件包。

```
bitbake core-image-minimal
```

![Start bitbake](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/bitbake_coreimageminimal.png)

**非常重要的是要在普通 Linux 用户下运行上面的命令，而不是使用 root 用户**。如下面截图所示，当你在 root 用户下运行 bitbake 命令会产生下面所示的错误。

![Do not run bitbake as root](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/dont_user_as_a_root.png)

再一次运行导出环境变量的脚本（`oe-init-build-env`），重新执行相同的命令来启动下载和编译过程。

![rerun commands](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/runniing_bitbake_again-normal_user.png)

如下所示，构建脚本组件的第一步工作是解析配置（`recipe`）。

![Parse the build recipes](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/parsing-receipe.png)

下面的截图展示了构建脚本的解析过程。同时也显示了用来构建你的新的基于 yocto 的发行版的构建系统的细节。

![Building proceeds](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/output_of_parsing.png)

在下载了 SDK 和必要的库之后，下一步工作是下载并编译软件包。如下截图展示了为构建新发行版而执行的任务。这一步将会执行 2-3 小时，因为首先要下载需要的软件包，然后还要为新的 Linux 发行版编译这些软件包。

![Compilation will take several hours](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/task_list.png)

下面的截图表明了任务列表执行完毕。

 ![](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/downloaded-all_packages_and_compiled.png)

为目标机器类型 `qemux86-64` 编译好的新镜像位于 `build/tmp/deploy/images/qemux86-64`：

![Build complete](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/new_linux_compiled_under_qemux86_64.png)

如下所示，上面的命令如果运行在 `Putty` 上会产生一个错误。

![command error in putty](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/error_on_putty.png)

通过 `rdp` 在 Ubuntu 平台上再次运行上面的命令。

![Command works fine in rdp](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/runqemu_command.png)

为运行新的基于 Yocto 的 Linux 发行版的 qemu 打开一个新屏幕。

![Open Quemu emulator](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/new_linux_inside_the_qemu_.png)

下面展示了新发行版的登录界面，同时也显示了使用的 yocto 项目的版本号。默认的用户名是 `root` ，密码为空。

 ![Linux distribution started](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/reference_distro.png)

最后使用 `root` 用户名和空密码登录新发行版。如下截图所示，在这个最小版本的 Linux 上运行了基本的命令（`data` 、 `ifconfig`  和 `uname`）。

 ![Test the Linux distribution](https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/inside_new_linux_distro_running_on_qemu_3.png)

本文的目标是理解使用 Yocto 创建新的 Linux 发行版的过程。

--------------------------------------------------------------------------------

via: https://www.howtoforge.com/tutorial/how-to-create-your-own-linux-distribution-with-yocto-on-ubuntu/

作者：[Ahmad][a]
译者：[Ezio](https://github.com/oska874)
校对：[wxy](https://github.com/wxy)

本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出

[a]:https://www.howtoforge.com/tutorial/how-to-create-your-own-linux-distribution-with-yocto-on-ubuntu/
[1]:https://www.howtoforge.com/tutorial/how-to-create-your-own-linux-distribution-with-yocto-on-ubuntu/#prerequisites-for-the-development-machinenbsp
[2]:https://www.howtoforge.com/tutorial/how-to-create-your-own-linux-distribution-with-yocto-on-ubuntu/#yocto-compilation-and-building-process
[3]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/1-pre_requisite_packages-1.png
[4]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/2-pre_requisite_packages-2.png
[5]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/download_morty_of_yocto.png
[6]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/source_environment_script.png
[7]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/selected_target.png
[8]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/uncheck_Download_parameters.png
[9]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/uncheck_sstate_parametes.png
[10]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/tempdir_uncheck_paramerter.png
[11]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/sdk_and_package_selection.png
[12]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/extra-features_for_blank_password.png
[13]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/bitbake_coreimageminimal.png
[14]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/dont_user_as_a_root.png
[15]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/runniing_bitbake_again-normal_user.png
[16]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/parsing-receipe.png
[17]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/output_of_parsing.png
[18]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/task_list.png
[19]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/downloaded-all_packages_and_compiled.png
[20]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/new_linux_compiled_under_qemux86_64.png
[21]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/error_on_putty.png
[22]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/runqemu_command.png
[23]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/new_linux_inside_the_qemu_.png
[24]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/reference_distro.png
[25]:https://www.howtoforge.com/images/how-to-create-your-own-linux-distribution-with-yocto/big/inside_new_linux_distro_running_on_qemu_3.png