[klibc] [PATCH] build: Define __EXPORTED_HEADER__

[Mike Waychison]

On Thu, Feb 24, 2011 at 6:19 AM, Arnd Bergmann <arnd at arndb.de> wrote:
> On Thursday 24 February 2011, Mike Waychison wrote:
>> The kernel header guard to ensure that headers aren't included from
>> userland moved in commit 69c8f52b.  This causes the following message to
>> be emitted when building klibc (which is designed to use kernel headers
>> explicitly):
>>
>> /usr/local/src/git/linux-2.6//include/linux/types.h:13:2: warning: #warning "Attempt to use kernel headers from user space, see http://kernelnewbies.org/KernelHeaders"
>>
>> In order to silence this warning, make sure we define
>> __EXPORTED_HEADERS__ when building klibc userland.
>>
>> Signed-off-by: Mike Waychison <mikew at google.com>
>
> Well, klibc uses the kernel headers, but I don't think it's a good idea
> to use them directly without make headers_install. Since klibc also
> doesn't set -D__KERNEL__, the result should be the same, except that
> it makes sure not to use any headers that are meant to be internal.

I'm not sure I follow.  The warning happens when __KERNEL__ isn't set.

Also, the build for klibc explicitly supports using kernel headers
without installing them first via setting KLIBCKERNELSRC.