On Thu, Oct 25, 2012 at 11:46 AM, Robert P. J. Day <rpjday@crashcourse.ca> wrote:
looking at the "uapi" reorganization in the kernel source for the first time, and a couple things confuse me.
i see the principle -- collect all the userspace API content in one place, in this case include/uapi/. this obviously(?) is supposed to represent a newer way to represent what you got formerly with
$ make headers_install
that is, header files identified in Kbuild files, cleansed of any kernel-only content, then placed under usr/include in the source tree. is that about right -- is that what it's supposed to represent?
Read this guy as well: http://lwn.net/Articles/507794/ So avoiding issues with double dependency is really another objective.
so at a *guess*, it would seem that, if a header file that should be part of uapi didn't need any cleaning, it could go straight into include/uapi untouched.
Yup.
on the other hand, if a header file *did* have some kernel-only content, i would have *thought* that there would be two versions of that header file:
a) the one with the kernel-only content still under include/linux, which would turn around and, in some way, include ..
It includes the respective uapi header as well.
b) the common content file under include/uapi
does that make sense? because i took a quick look and here's an example i don't understand. there's include/linux/coda.h, with the contents:
#if defined(__linux__) typedef unsigned long long u_quad_t; #else #endif #include <uapi/linux/coda.h> #endif
ok, so far, so good. but then there's this in include/uapi/linux/coda.h:
... snip ... #ifdef KERNEL <--- ????? typedef unsigned long u_long; typedef unsigned int u_int; typedef unsigned short u_short; typedef u_long ino_t; typedef u_long dev_t; typedef void * caddr_t; ... snip ...
Interesting, not sure. David ? I do see some BSD'ish deps there (#if defined(__NetBSD__))... so not sure if that was left to them or what.
why is there still kernel-only content in the uapi/ directory? maybe i just don't understand the rationale for what's going on here.
No, I'm as puzzled. Luis