I have read about FSF plugin policy

If modules are designed to run linked together in a shared address space, that almost surely means combining them into one program.

(Emphasis mine). Now there are environments where only one address space exists, such as the real-mode operating system FreeDOS. On FreeDOS you can think of each application/driver as a DOS plugin with that definition (only one address space means everything is in that address space). Can I distribute a proprietary game together with FreeDOS? Can I run it? Or will the distinction in that case be something else (in case of DOS, whether or not it is a TSR program)?

1 Answer 1


The traditional way to think of a shared address space is when you have a process that isolates memory regions. This of course would not apply to an OS that does not have a notion of a process. But would not FreeDOS allocate separate memory regions to each of the TSR? Actually the FreeDOS wiki is quite clear and explicit on this topic:

Additionally, distributors must share any changes they make under the same open source software license. For example, if someone adds native FAT32 support into the FreeDOS kernel, and shares that new kernel, then those changes also fall under the GNU GPL. However, if they add FAT32 support via an add-on TSR program and simply bundle it with the rest of FreeDOS, then the GNU GPL does not apply to that program.

The idea is to protect open source software and its authors. No one else should be able to take their code and misrepresent it, or worse, turn open source software into proprietary software.

There is your answer: an application or a TSR running on FreeDOS does not have to be GPL-licensed in general.

  • Does this mean that there is no official statement from FSF about this case, but each project give their own statement?
    – user877329
    Jun 7, 2016 at 11:08
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    Correct. And even if there was an official statement from the FSF (officially there is no such thing only a license text and commentaries), the stated interpretation of the author would matter most IMHO. Jun 7, 2016 at 11:32
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    @user877329: These things are called exceptions and there are several types. GPLv2 defines how each individual project (such as the Linux kernel) may add exceptions to the GPL license. That is what it seems FreeDOS is doing. So while there is no general statement from FSF, there is an official statement defining a mechanism of how projects may add exceptions. GPLv3 changed the language a bit and defined a general "system library exception" and adds a mechanism for how projects may add "permissions" to non-OS code
    – slebetman
    Jun 8, 2016 at 6:11

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