K 10 svn:author V 3 jhb K 8 svn:date V 27 2020-09-08T22:50:24.514532Z K 7 svn:log V 529 MFC 359900: Export a sysctl count of RX FIFO overrun events. uart(4) backends currently detect RX FIFO overrun errors and report them to the uart(4) core layer. They are then reported to the generic TTY layer which promptly ignores them. As a result, there is currently no good way to determine if a uart is experiencing RX FIFO overruns. One could add a generic per-tty counter, but there did not appear to be a good way to export those. Instead, add a sysctl under the uart(4) sysctl tree to export the count of overruns. END