[PATCH] tools: add libyaml

[Daniel Golle]

On Thu, Jul 30, 2020 at 02:55:33PM +0200, Petr Štetiar wrote:
> Paul Spooren <mail at aparcar.org> [2020-07-29 12:45:25]:
> 
> > Once available this can be used within a CI to reduce human resources
> > spent on reviewing DTS files.
> 
> That's indeed cool, but I quite fail to see why this needs to be in the tree
> right now. I would understand this patch as part of a bigger patch series
> which would add somehow minimal/proof-of-concept yet complete YAML/DTS
> validation support to the tree.
> 
> So in the end, both CI bot and developer on local machine could run same
> commands, like `make validate-dts target/linux/foo/dts/bar.dts` etc.

Yes, but this is only easily possible if dtc (in scripts/dtc/ in the
kernel tree) was build with support for libyaml. The easiest way to
achieve that is to have it built as a host tool.
This would allow for further integrating check_* features into OpenWrt
workflow similar to how we are already doing it for many other common
maintainance tasks (make package/foo/refresh, ...)

> 
> Meanwhile I would simply add all the missing bits into separate Docker image
> tailored specifically for DTS validation on CI. Or we could even add those
> bits into the `openwrt-ci/native-testing` container image.
> 

Sure, for the CI you can just make sure libyaml-dev is present in the
container...