How do I license my code that needs to include code under 'GPLv2 only', 'GPLv3' and 'BSD 3'?

Question

If I understand the table (mentioned at https://www.gnu.org/licenses/gpl-faq.html#AllCompatibility) correctly, I can use either 'LGPLv2.1 only' or 'LGPLv2.1 or later' for my code if I want to include code from both 'GPLv2 only' and 'GPLv3'. Is that correct?

Can I also include code from a 'BSD-3-Clause License' into my 'LGPLv2.1 only' or 'LGPLv2.1 or later' code? Given how permissive BSD-3 is, it seems like it can be included for my LGPL code but I am not sure.

So assuming the above is true and LGPLv2.1 (the two types mentioned above) can be used, how do I make my LICENSE file? Do I first include the notice for LGPL and then add a separate file that contains the BSD LICENSE? Is that all or am I missing something here?

Answer 1

No, you are misinterpreting the table.

The top-left entry you've highlighted ("I want to copy code under GPL v2 only" / "I want to license my code under LGPL v2 only") says that if you are the copyright holder of some code which you which to release under the LGPL v2 only, then you can copy some GPL v2 code and distribute the binaries - and in that case, the combination is under the GPL v2 only. This is not the same as your case where you are trying to combine multiple pieces of code on which you are not the copyright holder.

Unfortunately, you can't do what you want - code released under "GPL v2 only" is done so deliberately so it cannot be combined with GPL v3 code. You will have to find a replacement for one or the other pieces of code.