After i checked out and built firmware last night. I noticed that ps command doesn't take A x options anymore, this also make some script buggy which use ps to check process.
Here is the log,
root@OpenWrt:/etc/init.d# ps x
BusyBox v1.4.2 (2007-10-03 08:56:27 HKT) multi-call binary
Usage: ps
Report process status
Options:
w Wide output
I think it just take w option,