What exactly is the problem with the new Qt license? Afaik Qt 5.6 (currently used version in sfos) is licensed under LGPLv2.1. New QT versions (Qt 5.9 LTS, Qt 5.12 LTS) are released under LGPLv3… LGPLv3 should be completely OK for a library like Qt?
Or is the problem the new requirement in LGPL v3 which requires/enforces that users need to be able to rebuild/replace the Qt library binaries, which might be problematic for “locked down” installations of (corporate customer) phones? Even that should be completely OK for sfos distributions like SailfishX where the user has root access anyway…
How to Comply with LGPLv3
When you use Qt under LGPLv3, you have three main obligations.
- Your application should link the Qt libraries as shared libraries.
- You must make the Qt sources – including your modifications to the Qt sources – publicly available. For example, you can make available the Qt sources on your website or on GitHub for download. You can keep the source code of your application closed.
- You must enable users to build the Qt sources for the target device (e.g., an infotainment system in a car or a washing machine), deploy the Qt libraries on the target device and run the original application using the modified Qt libaries on the target device.
The first two obligations are the same as for LGPLv2.1. They are well-known and well-understood.
The third obligation is the so-called “anti-tivoisation clause“, which is Section “4. Combined Works” of LGPLv3 .
It actually forbids to fully lock down a device using software under LGPLv3.
A full lock-down was possible with LGPLv2.1 and was widely used.