ipc.h struct layout fix

[Peter Mazinger]

> On 07/07/11 20:41, Peter Mazinger wrote:
> > Hi,
> >> This fixes a problem identified by Mark Salter on C6X big-endian 
> >> systems. We should not use "unsigned short int mode"; the proper
> >> type is in theory mode_t, but here we need to use kernel_mode_t
> >> since this structure is used for communication with the kernel, and
> >> some targets have a 16-bit kernel_mode_t and 32-bit mode_t.
> > 
> > haven't looked closely, but if this header gets installed on target,
> > [__]kernel_mode_t is not/should not be defined. If the structure is
> > not meant to be used on target, than it should be guarded (like
> > _LIBC), else we should use mode_t here and handle accordingly in
> > code.
> 
> Accordingly meaning...? Should we translate kernel structures to user
> structures here? That would get really ugly.

It is, we do that in some places already like xstatconv.c, where we provide a common stat structure. The sigaction implementation had also similar problems, at least 3 types of arch-specific structures are present, the members are not even the same (or in same order), vda intended to make changes, but sincerely I did not follow up how far the changes went.
 
> Can't we ensure that the necessary type is defined somewhere?

My understanding for a libc is that we try to expose to userspace a common interface, hiding specialities of the kernel.
Let's see what others think...

Regards, Peter
-- 
NEU: FreePhone - kostenlos mobil telefonieren!			
Jetzt informieren: http://www.gmx.net/de/go/freephone