Re: How much survives an install/reboot cycle?

On Mon, Nov 20, 2023 at 09:12:45AM +0800, Zhenlei Huang wrote:
> 
> 
> > On Nov 19, 2023, at 11:51 PM, bob prohaska <fbsd@www.zefox.net> wrote:
> > 
> > How much of a running system's state survives a reboot? I used to think
> > the answer was "nothing", but from time to time a second reboot behaves
> > a  little differently from the previous one. 
> 
> Warner has a good description about that. I totally agree.
> 
> > 
> > The most recent example was an update to bpf.c: Prior to the update an
> > armv7 system had been inclined to drop ssh connections left up for days.
> > After updating and running a build/install cycle the behavior persisted,
> > but since a second reboot with no intentional changes it has stopped.
> 
> The most recent change to bpf.c is 7a974a649848 (bpf: Make dead_bpf_if const) .
> It is not a functional change, and I do not think it will affect ssh.
> There could be issues under the earth.
> 

That is most helpful. Very likely the change I saw is simply coincidence.

> Anyway please do not hesitate to report if you get recovered by reverting 7a974a649848.

In this case I don't want to revert, the new behavior is desirable. My only puzzle was
the seeming delay in its appearance. 


The only consistent issue remaining is reported in Bug 273566 . It finally dawned
on me that the garbage characters must be originated on the USB end, transmitted
to the getty process watching the serial end and get stuck in the transmit buffer 
when the link goes down. When the serial link comes back up they appear on the
receiving console display. 

Many thanks to you and Warner!

bob prohaska