linux-kernel - Re: x86/fpu: Don't export __kernel_fpu

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Message-ID: <20190109111951.5zvnj7ls6jv56p2u@linutronix.de>
Date:   Wed, 9 Jan 2019 12:19:52 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Marc Dionne <marc.c.dionne@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        x86@...nel.org
Subject: Re: x86/fpu: Don't export __kernel_fpu_{begin,end}()

On 2019-01-07 18:08:26 [-0400], Marc Dionne wrote:
> On Thu, Dec 27, 2018 at 11:20 AM Linux Kernel Mailing List
> <linux-kernel@...r.kernel.org> wrote:
> >
> > Commit:     12209993e98c5fa1855c467f22a24e3d5b8be205
> >     x86/fpu: Don't export __kernel_fpu_{begin,end}()
> >
…
> >     With EFI gone as the last user of __kernel_fpu_{begin|end}(), both can
> >     be made static and not exported anymore.
> >
> This commit removes an exported function pair that is currently used
> by out of tree modules, while the replacement pair
> (kernel_fpu_begin/end) is EXPORT_SYMBOL_GPL.  So this is making
> existing functionality GPL only, which will probably be an issue for
> several out of tree modules that use the fpu.
> 
> Could kernel_fpu_begin/end be made plain EXPORT_SYMBOL?

It can be used by OOT modules as long as they are not under a
proprietary license. The change here is not for me to decide, I added
the x86 maintainers to make their decision. I can make a patch if they
say so.

On the other hand could we just drop EXPORT_SYMBOL_GPL? I doubt this
helps in any way yet please correct me if I am wrong. 
The kernel is GPL and everything links to it should be GPL compatible. People
that don't specify a GPL compatible license either use wrapper around their
binary blob or use EXPORT_SYMBOL functions. The latter group complains each
time a function is not available anymore and we end up changing it to
EXPORT_SYMBOL.
So what do we gain from that EXPORT_SYMBOL_GPL?

> Marc

Sebastian