Hi! I think I know what the problem is and is really really stupid.
The age of my systems was the correct hint here: The filesystem /usr is on is too old and it does not have microsecond resolution but the CPU is fast enough to get the job done in under a second. Which means the test is so fast, that the test.c is compiled once and then for every other test make just skips the compilation because it thinks the result is recent enough. The systems where this works reliably have microsecond resolution. If I add the switch "-B" to the make command in gen_compat_def I can reliably get the test to work correctly even on the systems with the older filesystem: cmd="make -s -B -C $KDIR M=$PWD modules" (To test my theory I added a "sleep 2" into the kbuild_test_compile() function and got the same correct result every time.) Argh! Grüße, Sven
