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From: David Howells <dhowells@redhat.com>
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To: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: dhowells@redhat.com, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org, arnd@arndb.de, tglx@linutronix.de,
        mingo@kernel.org, davej@redhat.com
Subject: Re: [PATCH 00/13] UAPI header file split
Date: Wed, 25 Jul 2012 12:20:32 +0100
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Michael Kerrisk <mtk.manpages@gmail.com> wrote:

> >> 2. EMPTY UAPI HEADERS
> >>
> >> Some of the resulting uapi header files are empty:
> >> ...
> >> I imagine this should be reasonably easy to fix.
> >
> > Fix how?  The Kbuild files say these headers must exist in UAPI space, but
> > the __KERNEL__ guards therein don't define any content for them in UAPI.
> 
> I'm not sure of the answer here. It certainly seems odd to have a
> bunch of new empty header files in the kernel tree, which is why I
> commented on it. Without digging much deeper, I've no idea whether the
> Kbuild files can be (automatically?) modified not to require these
> empty files.

You can't get rid of the empty header files completely.  They're exported to
userspace and so userspace may require their presence.

I could put a guard in there just so they're not empty, I suppose.

> So, a manual fix may be in order?

Or just apply the removal regexp to each line before I write the UAPI header
out.  I'll have a play with it later.

David