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by wang_li 1335 days ago
That's plainly not true as there are plenty of intra-kernel interfaces that are tagged as GPL only and if your kernel module isn't GPL you can't use said interfaces. For example, they added the GPL tag to the floating point context switch functions which broke ZFS at the time.
1 comments
WastingMyTime89 1335 days ago
I don’t understand your comment. The kernel cares about its license which is indeed the GPL, yes.

But Linux didn’t go out of its way to be incompatible with ZFS out of ideology. Sun intentionally picked a license which would not be compatible. That’s why ZFS lives outside of the main tree.

The ideology that’s driving the Linux kernel development: “shared source code leads to better code, user land should never be broken” are very different from the one that led to GCC gimping itself. Generally speaking the kernel community is very technically oriented and doesn’t go out of its way to prevent things for social reasons.

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wang_li 1335 days ago
The kernel devs went out of their way to label a whole bunch of kernel functions as GPL only. It's not about mainlining third party kernel modules, it's about not letting non-GPLed modules use certain functions in the kernel. This includes the fully open source OpenZFS project. It's not about CDDL / GPL incompatibilities. For OpenZFS it was some FPU context switching functions that had to be worked around when the kernel team labelled those functions as GPL only.

See: https://github.com/openzfs/zfs/issues/13042

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WastingMyTime89 1335 days ago
You seem confused. There is no mysterious GPL only label in the kernel. The whole thing is licensed under the GPL v2 period. It’s just that some ABI were broken for an unrelated reason as Linux doesn’t guaranty ABI stability and OpenZFS can’t find an alternative which satisfy their dependency needs. The kernel team doesn’t care about out of tree code when making changes. It has always been the rule.
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palunon 1335 days ago
> There is no mysterious GPL only label in the kernel

EXPORT_GPL_ONLY

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WastingMyTime89 1334 days ago
Yes, you are right. I didn’t know the API was tagged. My take seems indeed a bit too extreme.

The kernel does care about enforcing the GPL explicitly on some of the interface it presents to modules to ensure the openness of the code which is indeed a form of statement in favour of open code.

I don’t think the situation was the same regarding compiling only with GCC - after all clang is free software - and I think the heart of my argument still hold: the kernel community makes decisions mostly for reason related to the kernel - even there they just want to force code to be mainlined - rather than for the movement like the FSS.

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