Re: call traces in xl dmesg during boot

[Jan Beulich <jbeulich@xxxxxxxx>]

On 29.10.2020 09:22, Olaf Hering wrote:
> During boot of xen.git#staging, Xen seems to think something pressed debug 
> keys very early, which shows various call traces in 'xl dmesg'. A reboot may 
> "fix" it, and no traces are printed.

I'm seeing the same every now and then, albeit only with a single
'A' so far, iirc.

> Any idea what may cause this behavior? I do not see it on a slightly smaller 
> box.

I've been assuming this is stuff left in the serial port's input
latch or FIFO. So far I didn't have a good idea how to tell
left over garbage from actual input that was sent very early, so
I've no good idea how to work around it. A command line option
triggering the discarding of initially present input doesn't
look very attractive to me ...

Jan