Yocto:在图像配方中创建符号链接 [英] Yocto: create a symlink in an image recipe

问题描述

我有一个自定义的 Yocto 'image' 配方，它使用 IMAGE_INSTALL += "... " 来构造图像，其中也包含 Python 3.5.不幸的是，没有创建常用的 /usr/bin/pdb 符号链接，我的用户希望能够从命令行运行 pdb.所以我想在图像中为此制作一个符号链接.如果它在目标上运行，它将是以下命令的结果:

I have a custom Yocto 'image' recipe, that uses IMAGE_INSTALL += "... " to construct the image, which also contains Python 3.5. Unfortunately, the often-used /usr/bin/pdb symlink is not created, and my users expect to be able to run pdb from the command line. So I want to make a single symlink for this, within the image. If it were run on the target, it would be the result of this command:

ln -s/usr/lib/python3.5/pdb.py/usr/bin/pdb

我知道我可以使用这种构造在图像配方中创建自定义任务:

I understand I can create a custom task in the image recipe with this sort of construct:

addtask create_pdb_symlink before do_image
do_create_pdb_symlink () {
    ln -s /usr/lib/python3.5/pdb.py ${D}/usr/bin/pdb
}

然而，这不起作用，因为我猜测使用 ${D}，而且我认为文件系统在那个时候没有上演.它生成此错误:

However this doesn't work because I'm guessing at using ${D}, and I don't think the filesystem is staged at that point. It generates this error:

DEBUG: Executing shell function do_create_pdb_symlink
ln: failed to create symbolic link 
'/home/user/project/build/tmp/work/custom-linux/my-image/1.0-r0/image/usr/bin/pdb': No such file or directory
WARNING: exit code 1 from a shell command.

检查文件系统确认 /home/user/project/build/tmp/work/custom-linux/ 存在，但 /home/user/project/build/tmp/work/custom-linux/my-image 没有.

Inspecting the filesystem confirms that /home/user/project/build/tmp/work/custom-linux/ exists, but /home/user/project/build/tmp/work/custom-linux/my-image does not.

在那个 custom-linux 目录中有一些目录，其中之一被称为 rootfs 并且看起来非常有用，但我不确定我的任务是否应该是在 my-image 目录下翻找.

There are some directories in that custom-linux directory, one of which is called rootfs and looks suspiciously useful, but I'm not sure if my task should be poking around below the my-image directory.

所以我的问题是:

• 这是正确的方法吗?
• 还是我应该创建一个全新的配方来构建这个单一的符号链接?
• 还是我应该创建一个 python3-core.bbappend 来完成这项任务?
• 或者有什么原因不是由 python 配方本身创建的?

推荐答案

由于此符号链接显然与 python3 相关，因此我建议您使用该配方的 bbappend 创建它.配方名称是 python3_(version).bb，因此要捕获所有版本，将 bbappend 命名为 python3_%.bbappend.

Since this symlink is clearly related to python3 I would recommend that you create it using a bbappend for that recipe. The recipe name is python3_(version).bb, so to catch all versions name the bbappend python3_%.bbappend.

这应该有效:

# Create symlink at the end of do_install
do_install_append() {
    ln -sf /usr/lib/python3.5/pdb.py ${D}/usr/bin/pdb
}

# Include the symlink in the python3-debugger package
FILES_${PN}-debugger += "/usr/bin/pdb"

您也可以创建符号链接作为创建整个 rootfs 的阶段，但在这种情况下我不推荐它.但是，如果您在填充整个 rootfs 时需要做一些事情，请查看使用 ROOTFS_POSTPROCESS_COMMAND.例如.把它放在你的图像配方中:

You can also create symlink as the stage where the whole rootfs is created, but in this case I would not recommend it. But if you have something so need to do when the whole rootfs is populated look into using ROOTFS_POSTPROCESS_COMMAND. E.g. put this in you image recipe:

my_image_postprocess_function() {
    ln -sf /usr/lib/python3.5/pdb.py ${IMAGE_ROOTFS}/usr/bin/pdb
}

ROOTFS_POSTPROCESS_COMMAND += "my_image_postprocess_function; "

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