MISC-TN-014: Yocto and Debian packetization

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Revision as of 21:06, 10 August 2020 by U0002 (talk | contribs) (fix some internal wiki reference)

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Axel-04.png Applies to Axel Ultra
Axel-02.png Applies to AXEL ESATTA
Axel-lite 02.png Applies to Axel Lite
Yocto-logo.png Applies to Yocto

History[edit | edit source]

Version Date Notes
1.0.0 August 2020 First public release

Introduction[edit | edit source]

In recent years, the Yocto build system has gained popularity in the embedded world. Many silicon vendors such as NXP e Xilinx base their Board Support Packages (BSP) on this tool. Despite the fact that Yocto is very powerful and rich, it may be fairly tricky to use, however, especially during the development stage when developers generally need a lot of flexibility. In particular, the unavailability of an archive of prebuilt common packages—as opposed to most of server/desktop Linux distributions—can be really annoying. As described here, Yocto is basically devised to build an entire distribution from scratch indeed.

To mitigate this drawback, the technique described in this article can be used. In essence, one can build all the packages supported by Yocto (bitbake -k world) and make them available through a smart channel on a local server. Developers working on the target can easily install required packages without having to build them.

Interestingly, in recent BSP's, NXP indicates a little different approach, which goes even further as it is also open to interfacing to the Debian world. The following excerpt is taken from NXP i.MX Yocto Project User's Guide, Document Number: IMXLXYOCTOUG, Rev. L5.4.24_2.1.0, 06/2020:

Package Management

The default package management with Yocto Project is rpm. The i.MX distro now enables Debian as the package management. This can be easily turned off by add PACKAGE_CLASSES set to package_rpm to the local.conf (or creating a custom distro without the Debian package feed PACKAGE_CLASSES = "package_rpm"). With the addition of the Debian package feed, a sources.list can be added /etc/apt that links in Debian's package feed. This allows users to install packages not provided in the image without having to add them to a Yocto image. Because this package feed is not generated by the i.MX Yocto build process, there is no guarantee each package will work with the right dependencies but it allows simpler tools to be provided. Software that is complex and has more dependencies on specific versions might have issues with an external package feed.

In principle, the adoption of the Debian package management should allow to use prebuilt package archives available for Debian distributions. However, close attention should be paid when mixing packages of different distributions. For instance, Debian packages installed on a Yocto file system could not work. Even worse, they could interfere with existing packages and make these unusable.

This Technical Note (TN) describes a way to apply the approach illustrated here to a Yocto distribution that makes use of Debian packetization. In other words, a local archive of Yocto-generated, prebuilt .deb packages is used in combination with the well known apt-get utility.

Testbed[edit | edit source]

The testbed used to verify this procedure consists of an NXP i.MX8M Plus EVK (*) combined with the Linux BSP tagged as L5.4.24_2.1.0.

(*) At the time of this writing, the i.MX8M Plus SoC is not released yet. DAVE Embedded Systems, however, has access to the EVK because our company is part of the related Beta program.

Configuring and testing[edit | edit source]

First of all, all the packages were built with Yocto. Then, they were copied to a server supporting the HTTPS protocol. The resulting archive is available here: https://yocto.dave.eu/imx-5.4/.

On the target, the file /etc/apt/sources.list.d/imx-5.4.list was created in order to point to this archive:

root@imx8mpevk:/etc/apt/sources.list.d# cat imx-5.4.list 
deb https://yocto.dave.eu/imx-5.4/aarch64-mx8mp ./
deb https://yocto.dave.eu/imx-5.4/aarch64 ./
deb https://yocto.dave.eu/imx-5.4/all ./
deb https://yocto.dave.eu/imx-5.4/imx8mpevk ./

Please note that two .list files were automatically generated by Yocto: /etc/apt/sources.list.d/debian-10.list and /etc/apt/sources.list. They were renamed to debian-10.list.ignore and sources.list.ignore respectively.

The following example shows the installation of the git package, which is retrieved from the local archive:

root@imx8mpevk:~# apt-get install git
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/3043 kB of archives.
After this operation, 0 B of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
Install these packages without verification? [y/N] y
Selecting previously unselected package git.
(Reading database ... 99542 files and directories currently installed.)
Preparing to unpack .../git_2.23.1-r0_arm64.deb ...
Unpacking git (2.23.1-r0) ...
Setting up git (2.23.1-r0) ...
N: Ignoring file 'debian-10.list.ignore' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension