Building different machines & distros

[tirankas]

Hello,
If I build for a specific machine/distro and then build again (on the same build env) for different machine/distro, it seems the second build is totally messed up.
For example:
. ./setup-env --machine jetson-nano-emmc --distro mender
bitbake image-prod

Then:
. ./setup-env --machine jetson-xavier-nx-emmc--distro mender
bitbake image-prod
I see the new image is built for jetson-nano-emmc:
MACHINE = "jetson-nano-emmc"

Diving into the setup-env and setup-env-internal, I see the machine/distro is only picked up if build/conf/local.conf doesnt exist.

In my old system before jumping into the tegra-demo, my setup supports switching machine/distro with no issue.

Is this done like this purposely? Arent we missing the benefits of having the capability using build artefacts from one machine/distro to another without the need to rebuild anything from scratch?

Thanks

[madisongh]

You can easily build for a different machine in a single build workspace by setting MACHINE in the environment. For example

$ MACHINE=jetson-nano-emmc bitbake image-prod

In theory, you can do the same for DISTRO, provided that the other distro uses the exact same set of layers as the one you configured at setup time. That is not the case, however, for tegrademo and tegrademo-mender, since the -mender variant adds the Mender-related layers to conf/bblayers.conf.

And in practice, I've found, at least, that it's unsafe to assume that building different distros (for any Yocto-based setup, not just here) in the same workspace will ever work, in the general case. You're unlikely to get very much reuse (other than downloads) anyway, since distro-level configuration settings are likely to be different, and that affects all recipes in the build.

I usually have multiple build directories, one per distro in my setups:

$ . ./setup-env --machine jetson-xavier-nx-emmc --distro tegrademo

(which creates the default build subdirectory) and (in another window)

$ . ./setup-env --machine jetson-xavier-nx-emmc --distro tegrademo-mender build-mender

which creates build-mender for the other distro.

I then modify the DL_DIR and SSTATE_DIR settings to point to directories outside the build workspace for sharing between them.