Re: [RFC] Splitting out kernel<=>userspace ABI headers

["H. Peter Anvin" <hpa@zytor.com>]

Erik Andersen wrote:
> 
> That is certainly not what I was proposing.  Why are you bringing
> sys/stat.h into this?  The contents of sys/stat.h are entirely up
> to SUSv3 and the C library to worry about.  Nobody has proposed
> mucking with that.  I dunno about your C library, but mine
> doesn't include linux/* header files (not even sys/stat.h).  And
> I'd really like to fix uClibc to not use any asm/* either, since
> much of it is entirely unsuitable for user space.
> 

That's the whole problem here, isn't it, so let's fix it the sane way 
instead of putting Descartes before Dehorse.

Anyway, to answer your implied question is: since I explicitly don't 
have to worry about forward ABI compatibility, I expose the kernel ABI 
raw.  Thus I want to be able to use the kernel ABI directly, including 
for things like struct stat.  It poses a particularly interesting 
problem, actually, because the real stat system call is called stat64 on 
most platforms.

Thus, an ABIzed <linux/abi/stat.h> or whatever it's called might export 
  "struct __kabi_stat" and "struct __kabi_stat64" with the expectation 
that the caller would "#define __kabi_stat64 stat" if that is the 
version they want.  A typedef isn't good enough for C, since you can't 
typedef struct tags.

	-hpa