I spent a lot of time before the 8.1 release adding code to transparently map COMPAT_IA32 to COMPAT_FREEBSD32. I tested all kinds of different scenarios to make sure that it works, that it got error messages from old config programs, etc.
Today I got a complaint that COMPAT_IA32 doesn't work in 8.1-RELEASE. Linux module was failing to load properly. I thought it was really odd and that the folks complaining must be doing something wrong.
It turns out that I did something wrong. When I originally merged the work, I modified the options file, but didn't add the new options-compat file to stable/8 tree, so it didn't get merged into the releng/8.1 tree used to create 8.1. The result is that COMPAT_IA32 just fails silently in 8.1-RELEASE.
All that hard work ruined because I forgot to do a svn add... How disappointing.