For the OS image I use cpio.gz as file system. It gets booted as a RAMdisk. Sorry, forgot to mention that.

Building two different images doesn’t suit our use case. We install the image on a device and run different automated test suites on it, some of which need python. But for all of the testing time is critical.

I now have it running with the recipe I posted in the first mail in this thread. But I still can’t get rid of busybox in my python image.

Mit freundlichen Grüßen / Best regards
Norman Stetter
SW ENWICKLUNG EMBEDDED SYSTEMS
Garz & Fricke GmbH

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Von: Burton, Ross [mailto:ross.burton@intel.com]
Gesendet: Thursday, May 23, 2019 3:46 PM
An: Norman Stetter <Norman.Stetter@garz-fricke.com>
Cc: yocto@yoctoproject.org
Betreff: Re: [yocto] Building single package as image, respecting dependencies

On Thu, 23 May 2019 at 13:46, Norman Stetter <Norman.Stetter@garz-fricke.com<mailto:Norman.Stetter@garz-fricke.com>> wrote:
That seems to be a misunderstanding. I want to keep the OS image as small as possible to reduce boot time. We only use python for some test scenarios, so it doesn’t have to be included in the OS image. I did some measurements and including python3 in the OS image increased the boot time by over 30%. So the idea is to have it separately, and only mount it, when needed.

What filesystem are you using?  I wasn't aware of any modern file systems where the number of files installed affected mount performance.

Could you just build two images and have a 'normal' image and a 'test image'?  This is basically what the tools-testapps image feature is for.

Ross