If you run
jtreg by making a symbolic link to
linux/jtreg in another directory already on your
PATH you will need to export a
JT_HOME environmental variable.
If your version of Xcode is older than 3.2.5, the 32-bit build (java -d32 ...) won't start, but the 64-bit build will.
XToolkit currently does not function under 32-bit in universal builds.