Re: [GIT PULL v2] Kbuild updates for v5.15-rc1

On Mon, Sep 06, 2021 at 11:52:18PM +0200, Jakub Jelinek wrote:

On Mon, Sep 06, 2021 at 02:08:58PM -0700, Linus Torvalds wrote:
There is a stddef.h include too and that's it
(I must say I don't see the reason for that include though).

Yeah me neither.  Maybe the header used NULL before?

Other compiler provided headers (not talking about C++ now) also have no
or very limited includes, including stddef.h, stdarg.h, stdatomic.h, etc.
The only exceptions are tgmath.h which isn't usable without libc
math.h/complex.h,

<tgmath.h> is only for hosted environments.  That requires a C library
for GCC (we do not implement this stuff ourselves).  The compiler and
the C library have to work together to get this done, and the relation
between GCC and Glibc has been a bit too tight for this, it is true.

But a kernel build is not in a hosted environment.

in some cases stdint.h and limits.h which are in some
configurations provided both by the C library and the compiler and include
each other in that case (but e.g. stdint.h has an alternate version that
only uses compiler provided builtin macros) and openacc.h.

On what targets is <stdint.h> still problematic?  And <limits.h>?


Segher