On Friday, 18 June 1999 at 13:45:42 -0600, Wes Peters wrote: > Greg Lehey wrote: >> >> I've been away from work for several weeks, and I now find that I can >> no longer start remote serial gdb. I am using sio0 on the debugged >> machine side, and sio1 on the debugging machine side. Here are the >> relevant dmesg outputs: >> >> panic (debugged machine): >> >> sio0: system console >> sio0: gdb debugging port >> ... >> sio0 at port 0x3f8-0x3ff irq 4 flags 0x90 on isa0 >> sio0: type 16550A >> >> freebie (debugging machine): >> >> sio1 at port 0x2f8-0x2ff irq 3 on isa0 >> sio1: type 16550A >> sio1: interrupting at irq 3 >> >> I can communicate fine using cu, and a breakout box shows all modem >> signals asserte (DCD, DTR, DSR, RTS, CTS). When I go into remote >> debug on panic, RxD flashes, and when freebie tries to attach to >> panic, TxD flashes, so I'm obviously addressing the correct ports. >> I've checked the bit rate and configuration of the ports before going >> into debug, and they look right (9600 bps, cs8, -istrip, -parenb). I >> don't know what else to look for. Any ideas? > > I think you need flags 0x50 (instead of 0x90) on panic. From sio(4): > > Meaning of flags: > ... > 0x00010 device is potential system console > 0x00020 device is forced to become system console > 0x00040 device is reserved for low-level IO (e. g. for remote > kernel debugging) > ...
In fact, it was all OK. The serial port seems to be flaky. It works OK at 9600 bps, but drops characters at 38400. I'm still investigating whether this is hardware or software: it seems to work fine in normal mode, but when it's in serial debug mode it can often drop two characters at a time, and there's no overrun indication. Greg -- See complete headers for address, home page and phone numbers finger g...@lemis.com for PGP public key To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-hackers" in the body of the message
