Re: [PATCH] x86 byteorder.h: use __asm__/__inline__ for userspace

H. Peter Anvin
2008-12-27T20:46:18Z

Mike Frysinger wrote:
> On Saturday 27 December 2008 14:23:19 H. Peter Anvin wrote:
>> Mike Frysinger wrote:
>>> {su}{8,16,32,64} doesnt matter too much to me vs {u,}int_t{8,16,32,64}_t.
>>> as long as people stop using __{su}{8,16,32,64}. using the latter
>>> though does mean headers will more likely be "just usable" w/out needing
>>> linux/types.h include. but then people would be forced to include
>>> stdint.h or similar before a linux header ... and that sucks.
>> That is a total non-starter. This would mean that the C library itself
>> cannot use these headers without exporting additional symbols into the
>> namespace, *WHICH IT IS NOT ALLOWED TO DO*.
>
> which is already happening today you mean. grep the kernel headers and you'll
> see a ton of [u]intXX_t hits.

Now, keep in mind this is only true for headers exported to userspace.
But this is correct - which is the base of this conversation (Sam
suggesting that they should be warned about, and I suggested
auto-converting them.)

> this logic though means that the kernel should not be defining any structures
> that the C library is defining (such as asm-generic/fcntl.h). such structs
> should get renamed the same way as __[us]XX types

This is also correct, at least for exported headers. For
kernel-internal headers, it doesn't matter. Unfortunately we do have at
least several cases of exported interfaces with globally visible names.

There is one other exception of note, which is a header file which can
only be included by the userspace *application*, using a nonportable
top-level include (either directly <linux/*> or indirectly via <sys/*>).
In those cases we can be looser about at least structure names. This
is common for ioctl structures.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.