Even though I had a successful run with this before, I cannot repeat the experiment though I think I'm doing everything the same.
I'm taking my .rsf .rmf and .saf files from the target and running them through buildtbxxsc.
I was getting the error:-
Assertion failed: mrA->recLength >= k, file C:vtunebuildXSCCollectorSrcXSCUtilBuildTB5XSCStartBuildTB5.cpp, line 409
abnormal program termination
But having tried to replicate exactly my initial success with the whole process (i.e. same app as before, same clock speed, same vtlxsc commandline string, jffs2 not nfs, etc, etc), I'm now getting told that 'Module file is not of valid format! BuildTB5 terminated: unable to add modules into sample file'.
The contents of the file do look sensible though.
I'm running PXALinux on a Mainstone 2.