For Linux, Solaris, BSD, and AIX the implementations of vmError support (vmError_<os>.cpp) are very similar, with many of the differences being merely code formatting and spelling, capitalization, and formatting in comments. Many of the remaining differences look like they could be reconciled, perhaps with a few much smaller os-specific helper functions.

So I think these vmError_<os>.cpp files could be mostly merged into a single implementation in os/posix.