Hi Rob,

On 14/09/21 2:51 am, Rob Herring wrote:

It is possible to build a single dtb, but not with DT schema validation
enabled. Enable the schema validation to run for %.dtb and %.dtbo
targets. Anyone building a dtb for a specific platform *should* pay
attention to schema warnings.

This could be supported with a separate %.dt.yaml target instead.
However, the .dt.yaml format is considered an intermediate format and
could possibly go away at some point if schema checking is integrated
into dtc. Also, the plan is to enable the schema checks by default once
platforms are free of warnings, and this is a move in that direction.

Just started building 5.16-rc4 and hit the following error

/usr/src/linux/scripts/dtc/Makefile:23: *** dtc needs libyaml for DT 
schema validation support. Install the necessary libyaml development 
package..  Stop.
make: *** [/usr/src/linux/Makefile:1405: scripts_dtc] Error 2
make: *** Waiting for unfinished jobs....

I tracked it back to this patch and I gather that the "error" is very 
much intended. Fixing it means I need to get a native libyaml into my 
cross toolchain, which is doable but a bit of a hassle. This probably 
affects other meta build systems like buildroot and yocto.

I think I understand what you're getting at but is it possible to have 
some kind of escape hatch to avoid having to add a build time tool 
dependency (or even bundling libyaml next to scripts/dtc)?

I also notice that when I do supply a toolchain with libyaml the build 
times are impacted by a noticable factor.