An issue is backwards compatibility for those systems. If they use
32 bit values for the file size in struct stat today, they have to
accomodate a structure change anyway. Sure, this is possible, like
the __xstat hack in libc/x86 shows (is that used on the other
architectures?).
So you have:
- to support old binaries with the old interface, preferably with the
same libc image as the new interface.
- to recompile all interesting applications to take advantage of the
interface change.
- to modify the source code of those applications so that they run
on x86.
Together, this makes it not really necessary to extend the old
interface to 64 bits.
As a first step, we need the kernel support, anyway.
Regards,
Martin