On Fri, Jan 07, 2022 at 06:01:39PM +0000, Laura Smith wrote: > Hi > > I'm having a really weird experience on a 6.9 box trying to connect to a > switch serial console. > > If I run "cu -r" then I can see the switch (when the switch is running its > fine, I can interact with the CLI, but if the switch reboots, I just get > random characters)
So is it just during the boot sequence that you get noise, and then at some point you can access it again at 9600, or does rebooting it make it impossible to access again until you restart cu? Is there any hardware handshaking on this serial connection? Is the line noise actually always random characters or mostly ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ ? It sounds like the switch is simply using one baud rate during boot, and switching to 9600 afterwards. However, I have noticed when using cu on a 115200 baud link with no handshaking, that when sending more than about 2 or 3 kilobytes of text continuously at maximum speed, (using the local ~> escape), that the cu session can freeze and only be recovered by exiting and restarting cu. I also saw a kernel panic on one occasion, but was unable to reproduce it. I had assumed that this was a bug in the USB serial driver, but I haven't investigated it further and it may be something else.
