On Thu, May 2, 2019 at 8:41 AM Sebastian Andrzej Siewior
<bige...@linutronix.de> wrote:
>
> On 2019-05-02 07:42:14 [-0700], Andy Lutomirski wrote:
> > The FPU is not a super-Linuxy internal detail, so remove the _GPL
> > from its export. Without something like this patch, it's impossible
> > for even highly license-respecting non-GPL modules to use the FPU,
> > which seems silly to me. After all, the FPU is a CPU feature, not
> > really a kernel feature at all.
> >
> > Cc: Sebastian Andrzej Siewior <bige...@linutronix.de>
> > Cc:: Borislav Petkov <b...@suse.de>
> > Cc: Rik van Riel <r...@surriel.com>
> > Cc: "H. Peter Anvin" <h...@zytor.com>
> > Cc: "Jason A. Donenfeld" <ja...@zx2c4.com>
> > Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
> > Cc: Dave Hansen <dave.han...@linux.intel.com>
> > Cc: Ingo Molnar <mi...@redhat.com>
> > Cc: Nicolai Stange <nsta...@suse.de>
> > Cc: Paolo Bonzini <pbonz...@redhat.com>
> > Cc: Radim Krčmář <rkrc...@redhat.com>
> > Cc: Thomas Gleixner <t...@linutronix.de>
> > Cc: x...@kernel.org
> > Cc: sta...@vger.kernel.org
> > Fixes: 12209993e98c ("x86/fpu: Don't export __kernel_fpu_{begin,end}()")
> > Signed-off-by: Andy Lutomirski <l...@kernel.org>
> > ---
> >
> > This fixes a genuine annoyance for ZFS on Linux. Regardless of what
> > one may think about the people who distribute ZFS on Linux
> > *binaries*, as far as I know, the source and the users who build it
> > themselves are entirely respectful of everyone's license. I have no
> > problem with EXPORT_SYMBOL_GPL() in general, but let's please avoid
> > using it for things that aren't fundamentally Linux internals.
>
> 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.
> Also with the recent FPU rework it is much easier to get this wrong so I
> would not want for any OOT code to mess with it.
>
I'm not saying that we should export things for ZFS's benefit. But,
as far as I know, _GPL means "this interface is sufficiently specific
to Linux details that we think that any user must be a derived work".
I don't think that kernel_fpu_begin() is an example of that.
--Andy
