Thank you both for the discussion on licensing. Seems that GPLv3 is a good choice for now. Wikipedia seems to claim that ReactOS is licensed under "GPLv2 or any later version" but I didn't find this on the reactos source code itself. If the ReactOS foundation has an objection later I can always change it to v2. Best, Chang On Wed, Feb 23, 2022 at 12:09 AM G. Branden Robinson < g.branden.robinson@gmail.com> wrote:

Hi Chamg,

At 2022-02-22T23:29:21-0500, Chang Liu wrote:

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I just added a LICENSE file which is GPLv3.

Good choice!

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I'm honestly not sure what the difference between GPLv2 and GPLv3

There are modest differences, but the general thrust of both versions of the license is the same: guaranteed access to source code under a "share and share alike" principle.

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is so I went with the latest version (I assume they are compatible?)

Technically, no. But most GPLv2 software is licensed under terms that allow promotion of the license to "any later version". One famous example of an exception that is GPLv2-only is the Linux kernel. So is seL4 itself[1]. Consider whether you expect to need to share code with a GPLv2-only project. (Even if you do, I would only revisit your decision once concrete code-sharing is imminent.)

You're not stuck with a choice of a single license forever. The GPLv3 is a good selection to start with (in my opinion) because most organizations that would like to exploit a work for proprietary advantage are allergic to that license.

You can always relicense a work under more permissive terms later if doing so would align better with your goals. Going from more permissive terms (like a BSD-style license) to a copyleft (like any version of the GPL) can be impractical, or result in unintended consequences, because it is arguably impossible to rescind the permissive license on the older versions of the code--unless you have an Apple- or Oracle-sized budget for lawyers to intimidate rivals maintaining the old code base.

There is probably a better forum for licensing discussions, but my view is that you've made a perfectly reasonable choice, one that situates your project squarely and clearly within the Free Software community, while still leaving you the option to reconsider later.

Regards, Branden

[1] https://microkerneldude.org/2019/12/09/what-does-sel4s-license-imply/