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

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Message-ID: <nycvar.YFH.7.76.1905040849370.17054@cbobk.fhfr.pm>
Date:   Sat, 4 May 2019 09:26:19 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     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,
        stable@...r.kernel.org
Subject: Re: [PATCH] x86/fpu: Remove the _GPL from the kernel_fpu_begin/end()
 export

On Fri, 3 May 2019, Jiri Kosina 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.

... any for many uses that's really the only thing that's needed.

	kernel_fpu_beign();
	asm volatile ("some SSE2/AVX/... math");
	kernel_fpu_end();

No other bits of the FPU API, so there is no way of getting anything wrong 
because of FPU intrinsic details really.

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 :)

-- 
Jiri Kosina
SUSE Labs