Re: Boot stops at loader after build/install cycle

On Wed, Mar 29, 2023 at 08:47:20AM +0000, Marcin Cieslak wrote:
> 
> Type '?' for a list of commands, 'help' for more detailed help.
> OK 6;176R
> 
> sometimes the extra characters are different, like
> 
> OK 9;106R
> 
> Is this some device status report sequence of the terminal or something?

I've never seen any extraneous characters at the loader prompt on
the serial end. I do sometimes see extraneous characters on the
usb end after establishing a connection to a booted host and
getting a login prompt. Those have always been "^@^@^@^@^@....."



> 
> It seems to boot fine with three wires connected to the CH341, but
> "tip" session must be disconnected. tip is running in rxvt-unicode
> (TERM=rxvt-unicode-256color), running in x11-wm/dwm under Xorg.
> 
> With three wires disconnected (nothing plugged in, only USB power and
> the Ethernet), it works pretty unreliably. Sometimes it simply stops
> working and simple power cycle does not bring FreeBSD back (unless
> I connect the console and observe things). But maybe this is something
> different. Of course now at my desk as I write this it boots every time :)
> but not so in the field. (But that is probably something unrelated).
> 

Does anything change if you use cu? cu -l cuaU0 -s 115200 for example.

If not maybe try  different hardware (cables, usb-serial adapters, 
power supplies and so on) with an eye to any changes of behavior. 
At this stage making the problem worse might be more useful than 
making it better. Disconnecting the serial-end ground might be 
worth a try. If the connection still works it suggests you have
multiple grounds, which can cause trouble. I ended up lifting
the ground on one of my serial connections. AFAIK both Ethernet
and USB power supplies are floating, so multiple grounds are very
unlikely. But something might be faulty. 

I've put some "notes to self" at
http://www.zefox.net/~fbsd/pi_serial_console
and
http://www.zefox.net/~fbsd/console_wiring

hth,

bob prohaska