Re: include/linux/xattr.h: how much userpace visible?

[Christoph Hellwig <hch@infradead.org>]

On Mon, Feb 26, 2007 at 03:52:42PM -0800, H. Peter Anvin wrote:
> David Miller wrote:
> >>>
> >>However, it would be better if the ABI constants were exported, or at 
> >>least *exportable* (using a __KERNEL_XATTR_MACROS test macro or 
> >>something like that.)
> >
> >This is the same situation as the socket.h issue we're trying
> >to figure out what to do about.
> >
> >wrt. the socket.h case I think I'm going to revert the guilty
> >changeset for now until a better scheme is implemented
> 
> Indeed it is (as well as <linux/stat.h>).
> 
> I believe the use of feature macros is probably the way to go; that way 
> userspace can request subsets, which can vary from libc to libc.
> 
> There is, of course, the "ABI language" variant, but I don't see that 
> happening unless someone has a lot of time to spend on it.

What's the problem of exposing all these APIs unconditionally?
glibcs should either use all information from the linux/ headers
or nothing at all, but not depend on hiding some bits.