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Date:   Sat, 4 May 2019 02:47:47 +0200
From:   Ingo Molnar <mingo@kernel.org>
To:     Jiri Kosina <jikos@kernel.org>
Cc:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Andy Lutomirski <luto@kernel.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Rik van Riel <riel@surriel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Nicolai Stange <nstange@suse.de>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, x86@kernel.org,
        stable@vger.kernel.org, Jiri Kosina <jikos@jikos.cz>
Subject: Re: [PATCH] x86/fpu: Remove the _GPL from the kernel_fpu_begin/end()
 export
Message-ID: <20190504004747.GA107909@gmail.com>
References: <761345df6285930339aced868ebf8ec459091383.1556807897.git.luto@kernel.org>
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* Jiri Kosina <jikos@kernel.org> wrote:

> On Thu, 2 May 2019, Sebastian Andrzej Siewior wrote:
> 
> > Please don't start this. We have everything _GPL that is used for FPU
> > related code and only a few functions are exported because KVM needs it.
> 
> That's not completely true. There are a lot of static inlines out there, 
> which basically made it possible for external modules to use FPU (in some 
> way) when they had kernel_fpu_[begin|end]() available.
> 
> I personally don't care about ZFS a tiny little bit; but in general, the 
> current situation with _GPL and non-_GPL exports is simply not nice. It's 
> not really about licensing (despite the name), it's about 'internal vs 
> external', which noone is probably able to define properly.

But that's exactly what licensing *IS* about: the argument is that 
'internal' interfaces are clear proof that the binary module is actually 
a derived work of the kernel.

(Using regular exported symbols might still make a binary module derived 
work, but it's less clear-cut.)

So don't be complicit with binary module authors who try to circumvent 
the GPL by offloading the actual license violation to the end user ...

> If it would be strictly about license compatibility, that'd at least 
> make us somewhat deterministic.

License compatibility is rarely deterministic to begin with, there's a 
lot of grey area. Adding _GPL increases the likelihood that the module 
using it has to be covered by the GPL too. In fact behavior of binary 
modules seems to confirm that legal expectation: very few binary modules 
are trying to circumvent _GPL symbols by ignoring the _GPL attribute.

Anyway, in terms of _GPL exports the policy has always been that if a 
major author of the code asks for a symbol to be _GPL, then it should be 
so, even if other authors have a different judgement.

Thanks,

	Ingo