ssize_t is for things that either return a size_t value or -1. It's never used for parameters. I don't think a vm_ssize_t makes any sense.
This is an odd way to use constructed the RPC interface for this, but we already have it and perhaps there was some reason to do it that way. You can just pass (vm_size_t) -1 as the value to indicate "no upper limit". That should work automatically without any special effort on the server side. Thanks, Roland
