On Wed, Sep 21, 2016 at 08:46:50AM -0400, Greg Troxel wrote: > dtyU0 is the right file. ttyU0 and dtyU0 are for the same device, but > dty is a dialout device that does not block waiting for carrier detect, > vs tty that by default blocks opening until CD is asserted. (Back when > I was young, we had 300 baud modems, with dialin from terminals and > dialout for uucp!)
Thanks for the explanation! I just found that com(4) points to tty(4) which explains this, but ucom(4) (where I had looked before) doesn't. > > At the same time, the USB keyboard and USB mouse stopped working, > > without anything visible in dmesg. > > > > I wanted other processes to finish before rebooting, so I waited. > > > > 4 hours later I saw the following in the kernel log: > > ehci_sync_hc: cv_timedwait() = 35 > > > > 4 hours later I tried rebooting, but had to press the reset button, > > 'shutdown -r' didn't work. > > > > Should I have used /dev/ttyU0 instead? > > > > I find it worrying that the USB mouse and keyboard stopped working > > without any kernel messages, and that the processes hung unkillably. > > I think you are running into either > > really serious bugs in our kernel, or > > a broken device that is causing way more trouble than it should > > > Did you remove the serial dongle? I have found that at times, pulling a > troublesome USB device resolves things. I just tried again, on a kernel with EHCI_DEBUG and UCOM_DEBUG. The device seems to want 115200 baud, so I used cu -s 115200 -l /dev/dtyU0 which showed some patterns when it worked, perhaps some self tests. I booted into single-user mode and after enabling ehci and ucom debug, I tried a couple of times to start cu, exit it (with "<ENTER>~."), and power off/on the device again. After about the 5th try, the NetBSD machine hung. There were no kernel messages when I unplugged or replugged USB devices, and even the PS/2 keyboard that is attached didn't work any longer. I didn't really know what to do with such a stuck system, so I rebooted. Any ideas what I should try next time? > Did you try on a netbsd-7 system? No, I'm only running -current on that machine, and the netbsd-7 machines I have are remote. Thomas
