linux-kernel - RE: [PATCH] x86/fpu: Remove the _GPL from the kernel_fpu

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Date:   Tue, 7 May 2019 10:31:28 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Jiri Kosina' <jikos@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
CC:     Andy Lutomirski <luto@...nel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Rik van Riel <riel@...riel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        "Ard Biesheuvel" <ard.biesheuvel@...aro.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Nicolai Stange <nstange@...e.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "x86@...nel.org" <x86@...nel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH] x86/fpu: Remove the _GPL from the kernel_fpu_begin/end()
 export

...
> So I don't really see a problem with Andy's patch. If we want to annoy
> external non-GPL modules as much as possible, sure, that's for a separate
> discussion though (and I am sure many people would agree to that).
> Proposal to get rid of EXPORT_SYMBOL in favor of EXPORT_SYMBOL_GPL would
> be a good start I guess :)

As a writer on an external non-GPL module I'd point out:
1 - Even if we wanted to 'upstream' our code it is very specific
    and wouldn't really be wanted/accepted.
    Even if accepted it would always be excluded from builds.
2 - It would take man-years to make it meet the kernel code guidelines
    and to make it portable (from x86).
    It also contains conditionals because it gets build for windows.
    I don't like a lot of it.
3 - Almost all the calls to kernel functions are through a 'wrapper'
    file that is compiled on the target system.
    About the only functions that are directly called are ones like memcpy().
4 - It wouldn't be that hard, and would still be GPLv2 if we built
    two loadable modules, one GPL and one non-GPL and put all our
    wrapper functions in the GPL one.
    We'd still need a small wrapper for the non-GPL module, but while
    Non-GPL modules are supported at all it wouldn't be much work.
5 - The continual tweaks for new kernel versions keep us in a job!

Some of the _GPL exports are a PITA:
- we can't reference count network namespaces (without creating a socket).
- we can't reference count 'pid' structures making sending signals tricky.
- I thing the PCIe error handling functions that we ought to be using
  are GPL.

At the moment we've not needed the fpu :-)

	David

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