DTC preprocessor

[arisav]

Hi

How can I extract device tree blob build from yocto?

I have found *.dtsi files from under build/tmp -folder and want quickly test some dts setting and build new dtb with dtc compiler directly. Dtc does not understand C preprocessor directives so there must be some precompiler phase first? How can I call that preprocessor directly with proper defines?

Ari

[gusarambula]

Hello Ari Savolainen,

The .dsi generally contain SoC-level definitions.

To generate a .dtb (binary) file, so basically compiling, you would need to initialize the toolchain and then use:
make ARCH=arm  dtbs

The device tree files, including the source files (.dts) are located in the case of our Yocto BSP on:

<BSP_DIR>/<BUILD_DIR>/tmp/work/<MACHINE>-poky-linux-gnueabi/linux-imx/3.14.28-r0/git/ach/arm/boot/dts

The following very informative document may also be of help.
https://community.freescale.com/docs/DOC-329664

I hope this information helps!

[arisav]

OK thanks, Here is (bash) command to do precompile dts files before calling dtc. 

cpp -nostdinc -I include -undef -x assembler-with-cpp $SRC > $TMP

[gusarambula]

Hello Ari Savolainen,

You should be able to compile without the extra parsing - as long as you're using NXP's BSP.

However, I would recommend looking at the link below, where there is an option for the precompiling you're looking for.

arm - Device Tree Blob (binary) - Unix & Linux Stack Exchange

I hope this helps!