Re: reboot hesitation on Pi3 running -current

On Tue, Nov 28, 2023 at 08:15:30AM -0800, bob prohaska wrote:
> On Tue, Nov 28, 2023 at 07:20:03AM -0800, Mark Millard wrote:
> > On Nov 28, 2023, at 07:10, bob prohaska <fbsd@www.zefox.net> wrote:
> > 
> > > A Pi3 running -current has taken to pausing during a shutdown -r in a strange way:
> > > It gets to: 
> > > 
> > > Hit [Enter] to boot immediately, or any other key for command prompt.
> > > Booting [/boot/kernel/kernel] in 5 second more detailed help.
> > > 
> > > It then stops at the OK prompt:
> > > 
> > > OK boot <---typing boot fails:
> > > 
> > > unknown command <---this looks strange, the kernel should already be loaded
> > 
> > A possibility here is garbage control characters, say before
> > the "boot". YOu might want to type just <return> to the first OK
> > prompt and see if you ever still get "unknown command" once you
> > do type just "boot" (and <return>).
> 
> IIRC I've done that in the past with the same result, but memory is hazy
> and an attempt at a second shutdown -r came back up without hesitation.
> 
> Another build/install cycle is running now, I'll be more careful next time.
> 
> > The fact that the countdown stopped at 5 (or other early value)
> > suggests such extra text at that point.
> 
> Rubbish on the serial console is a common  occurence, but it usually
> shows up when the USB end is taken down and brought back up. In this
> case the USB end remained up throughout the reboot cycle, no stray 
> characters were visible.
> 
> Thanks for writing!

This topic has come up before here, I believe.

I can confirm the same or very similar behavior on rpi4, and there's no
USB-serial to disconnect on the remote end, rather an actual serial
console server which is always-on.

Unfortunately it's not consistent behavior, i.e. sometimes the reboot
proceeds uninterrupted. Sometimes typing 'boot' proceeds normally,
sometimes typing 'boot' errors and then typing it again proceeds as
normal.

I too have been thinking it's spurious chars on the serial console at
various points, but I've yet to find a common behavior or consistent
method to reproduce. This doesn't happen on my other serial consoles,
FreeBSD or Linux. I also don't think it happened early on when this
rpi4 was running raspbian for a brief time, but I didn't play with
that setup very long.

So far I believe it's avoidable by not watching the serial console
during reboot, not necessary (I think) to disconnect the cable. But
obviously that defeats the purpose of the serial console vs. a blind
reboot.

I plan to upgrade my rpi4 to 14.0 just to see if anything changes. Iirc
from the relnotes, one of the changes in new release is 115200 is the
new default for serial communications, and I have some hope that maybe
some hard-to-find hard-coded 9600 may have been thwarting those of us
running with different speed infrastructure and console.

Since bob is running -current on his rpi3 though, my hope is probably
a longshot.

Cheers,
sr.