How do I modify device tree with 18.06 Image Generator

For Developers
1

How do I build an image with a modified device tree using the 18.06 snapshot Image Generator?

I want to add a few lines to the target dts file to define a pps-gpio source. I can do this if I download the build system and compile everything from scratch. However, this seems unnecessary as the Image Generator appears to contain everything required - the device tree source files and a dtc binary.

I have successfully made working images with the image generator, but when I modify the dts file, the changes do not make it into the new image. I have tried tracing the working of the build system, but it confusing so I thought I'd ask.

Specifically:
Target sytem MediaTek Ralink MIPS
Subtarget MT76x8
Target profile GL-MT300N-V2

Build image with:
make image PROFILE=gl-mt300n-v2 PACKAGES="luci pps-gpio"

I then modify target/linux/ramips/dts/GL-MT300N-V2.dts
make image PROFILE=gl-mt300n-v2 PACKAGES="luci pps-gpio"

2

You probably should be working with the full build system, not the image builder. The image builder is primarily intended to assemble pre-compiled "bits" into an image, not to build from source.

3

Thanks for the advice. Using the Image Builder could have been a lot faster, as my only x86_64 linux box is old and slow. However, it is a waste of time to use tools in perverse and obscure ways.

4

Try enabling ccache if you expect to build more than once. It should speed subsequent builds immensely.