On Thu, Apr 07, 2005 at 02:17:41PM -0700, Matthew Dillon wrote:
> The great thing about the compatibility layer idea is that we can
> automate the generation of the version A <-> B handling code, and
> the optimal 'the versions are the same' case degenerates down into
> a direct system call. GCC can't break structures down into
> program-accessible data structures (not without a lot of fuss, anyway),
> but DICE's C parser can and that means we can automate the generation
> of the code which does copies between two different versions of the
> same structure.
If all that has to be done would be that easy :) You can do most of that
already with preprocessor magic, but the real problems are semantic
differences, size changes and more.
Consider a library accessing struct stat linked against a newer libc.
With symbol versioning we can handle that, as long as the library doesn't
export stat itself. That's one of the things I'm currently thinking about.
Joerg