For many reasons. To keep the namespace clean for ISO C, POSIX, XPG4.
To decouple the libc's types from the kernel, as we plan on making some
changes underneath the hood.
> pppd _REQUIRES_ linux/pppd.h amongst others [some flags not present in
> glibc].
What pppd requires (if more than the <net/*.h> headers, and it would
seem not from the 2.3.x success report!), is its own copy of whatever
it thinks it ought to be getting from the kernel.
> Incidentally, glibc has no sound support. [the flags for doing, say, midi
> are in linux/...]
Glibc is also work in progress. There is some sound bits in the
2.1 development tree, I don't personally know that they are all there.
But if not, send a proper bug report, or better yet a patch.
> Linux's IP support is pretty ... wild... The basic IP tools don't compile
> with glibc [without some pretty hefty patching sometimes]. [ipfwadm,
> ifconfig, route and the like].
They do now, thanks to Phillip Blundel et al. They also do ipv6.
> And most Unix's don't have a kernel with a decent Posix-set of includes
> already present.
Huh?
r~