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Subject: Re: [RFC] Splitting kernel headers and deprecating __KERNEL__
From: David Woodhouse <dwmw2@infradead.org>
To: Alexandre Oliva <aoliva@redhat.com>
Cc: Matthew Wilcox <matthew@wil.cx>, David Howells <dhowells@redhat.com>,
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On Fri, 2004-11-26 at 09:47 -0200, Alexandre Oliva wrote:
> On Nov 25, 2004, Matthew Wilcox <matthew@wil.cx> wrote:
> 
> > On Thu, Nov 25, 2004 at 04:20:06PM -0200, Alexandre Oliva wrote:
> >> This means these headers shouldn't reference each other as
> >> linux/user/something.h, but rather as linux/something.h, such that
> >> they still work when installed in /usr/include/linux.  This may
> >> require headers include/linux/something.h to include
> >> linux/user/something.h, but that's already part of the proposal.
> 
> > That's going to take severe brain-ache to get right ... and worse,
> > keep right.  These headers aren't going to get tested outside the kernel
> > tree often.  So we'll have missing includes and files that only work if
> > the <linux/> they're including is a kernel one rather than a user one.
> 
> How about moving the internals (i.e., what's not to be exported to
> userland) from linux and asm elsewhere, then?
> 
> Sure, it means significantly more churn in the kernel, but there's
> going to be a lot of moving stuff around one way or the other.

Not really. The kernel code was what was _allowed_ to be using those
headers with those names in the first place; it was userspace which
shouldn't necessarily have been doing so.

> While at that, we could also split what's kernel internal for real and
> what's to be visible to external kernel modules as well.  So we'd have
> 3 layers of headers, instead of two.  I'm not sure this actually makes
> any sense though, since there might be lots of dependencies of headers
> for modules on internal headers.

All modules will be entirely dependent on the full set of kernel
headers. Let's not go there.

-- 
dwmw2

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