On amd64, some of the mt commands cause a message to be logged to syslog, such as
+WARNING pid 31794 (mt): ioctl sign-extension ioctl ffffffff80046d08
Fix: The c_code field in the command structure in /usr/src/usr.bin/mt/mt.c needs to be unsigned long to match the type of the second argument to ioctl as in the attached patch.
Patch attached with submission follows:
How-To-Repeat: mt seteotmodel 1
Change was committed in r228619. Thanks!