> What about programs that need kernel structures such as (for example)
> the ext2 superblock? Or programs that will be grovelling through kernel
> memory?
>
> We could have a completely separate header file that define those
> structures (and all of the various constants), but it would be a pain to
> keep them in sync with the evolving kernel code....
It shouldn't be that much of a pain - these structures can't change often
anyway, because it's usually desirable to make such things
binary-compatible with old versions of the programs.
But yes, the solution in this case is indeed for the programs in question
to define their own copies of any things they want.
p.