that old GNU/Linux argument

Alexandre Oliva aoliva at
Fri Jul 25 13:16:35 UTC 2008

On Jul 24, 2008, Nifty Fedora Mitch <niftyfedora at> wrote:

> Recall, the name of this line that joins the kernel (Linux) and
> application space (think HelloWorld, X-windows and more) is the "question
> I am asking".  Of interest the "omissions" in the list of system calls 
> commonly show up as hardware specific ioctl() side doors.

> Perhaps the answer is as simple as "glibc".  I suspect that Posix is
> slightly more apropos.

The interface is mostly Posix, although there are GNU extensions to
it.  The implementation of the interface (with or without extensions)
is provided by GNU libc.  GNU libc borrows little more than system
call numbers from Linux header files.  At times, even the headers with
this information had to be maintained separately from Linux, because
Linux developers didn't want these headers to be ever included by

That's why I say Linux offers only an ABI to userland; there's no
actual API to use from userland.  Whatever APIs there are, they're
provided by GNU libc.

Alexandre Oliva
Free Software Evangelist  oliva@{,}
FSFLA Board Member       ¡Sé Libre! =>
Red Hat Compiler Engineer   aoliva@{,}

More information about the fedora-list mailing list