I have finally have a cross compiler building, but encounter a new problem with a simple "Hello World" program not working. I get in GDB: Breakpoint 1, 0x102b4718 in startHeapProfTimer () (gdb) Continuing. Breakpoint 3, 0x102b4708 in stopHeapProfTimer () (gdb) Continuing. Breakpoint 1, 0x102b4718 in startHeapProfTimer () (gdb) bt #0 0x102b4718 in startHeapProfTimer () #1 0x1028d918 in scheduleWaitThread () #2 0x102b5dd0 in rts_evalLazyIO () #3 0x1028b674 in real_main () #4 0x1028b79c in hs_main () #5 0x100021dc in main () The program seems to loop in scheduleWaitThread, toggling the HeapProfTimer endlessly and nothing useful happens. Any idea what could be wrong, or how I could tackle debugging this problem. The native build of the same program with same compiler version (HEAD) works well. Under what condition is scheduleWaitThread supposed to return? How can I enable source debugging for RTS files? I should note that this is a big-endian target (PPC) and I have seen trouble with certain fields being wrongly swapped in the past, but IIRC those resulted in crashes. Cheers and thanks, Gabor