kconfig source code license GPLv2 vs. Apache 2.0 (?)

[0x5442]

While investigating possible ways how to add kconfig to one of my planned open source projects, I have noticed that ESP-IDF (which provides almost exactly the kind of experience I want) contains the kconfig source code directly in the code base. But after further research it seems there could be a licensing problem, because the kconfig source code is "Released under the terms of the GNU GPL v2.0." (as noted in the files), but ESP-IDF uses Apache 2.0 license and this combination is not compatible (?)

https://www.gnu.org/licenses/license-list.html#apache2:

Please note that this license is not compatible with GPL version 2, because it has some requirements that are not in that GPL version. These include certain patent termination and indemnification provisions0. ...

http://oss-watch.ac.uk/resources/apache2

... code that is licensed under the Apache License v2 cannot be combined with GPL v2-licensed code and distributed. ...

I am not a lawyer, so any insight would be greatly appreciated.

Thanks.

[ESP_igrr]

Kconfig is a host side tool which is used to configure the build, and isn't linked into the final firmware produced by this SDK. In this way it is similar, for example, to the GCC compiler which is GPL licensed and is used to produce the final application.

We will add a clarification to the copyrights page of the documentation.