[tbot] [fix] How to debug acquire_linux

Harald Seiler hws at denx.de
Fri Nov 23 14:54:29 UTC 2018


Hello again,

I pushed the fix[1] to the development branch, and with it I completely
phased out `login_wait`.  Please test this against your board configs
to make sure it doesn't break anything ...

I also added code to allow clobbering during login in preparation
for tackling that issue as well ... [2]

As soon as these commits hit master (next Wednesday probably), I will
update the `tbot-denx` repo to reflect these changes.

[1] https://github.com/Rahix/tbot/commit/70dc38ba0cc32cf3650cfe454d1f25cf938a31a5
[2] https://github.com/Rahix/tbot/commit/6a770d7456ec883e59f44c150e8f6366c9fe3306
-- 
Harald

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-62  Fax: +49-8142-66989-80   Email: hws at denx.de 

On Fri, 2018-11-23 at 13:24 +0100, Harald Seiler wrote:
> Hi Stefano,
> 
> On Fri, 2018-11-23 at 13:16 +0100, Stefano Babic wrote:
> > Hi Harald,
> > 
> [...]
> > It looks like that the additional traces change the time conditions. If
> > I run with -vvv works now, without not (in both cases login_wait=1
> > 
> > Anyway, the output with -vvv around the login is:
> > 
> > 
> > │   │    <>
> > │   ├─< 'GTU-0 login: '
> > │   ├─> 'root\n'
> > │   │    <> GTU-0 login: root
> > │   ├─> '\n'
> > │   ├─> "PROMPT_COMMAND=''\nPS1='TBOT-VEJPVC1QUk9NUFQK$ '\n"
> > │   ├─< 'root[   13.843245] NOHZ: local_softirq_pending 04\r\n[
> > 13.847350] NOHZ: local_softirq_pending 04\r\n\r\r\n[   13.864221] NOHZ:
> > local_softirq_pending 04\r\n[   13.868323] NOHZ: local_softirq_pending
> > 04\r\n[   13.872432] NOHZ: local_softirq_pending 286\r\n[   13.888457]
> > NOHZ: local_softirq_pending 80\r\n[   14.011121] NOHZ:
> > local_softirq_pending 04\r\n\x1b7\x1b[r\x1b[999;999H\x1b[6n'
> > │   ├─< '\x1b'
> > │   ├─< '8'
> > │   ├─< 'PROMPT_COMMAND='
> > │   ├─< "''\r\nPS1='TBOT-VE"
> > │   ├─< "JPVC1QUk9NUFQK$ '\r"
> > │   ├─< '\n'
> > │   ├─< 'root at GTU-0:~# '
> > │   ├─< "PROMPT_COMMAND=''"
> > 
> 
> Now this I can work with!  Ok, as you see, TBot sends it's shell init
> commands way before the shell is up.  Somewhere they get echoed anyway,
> this is to be expected.
> 
> Then, the shell comes up. It even reads the first command! But it stops there,
> the command is not executed even though we sent a \n.  I guess this is a
> mechanism in bash to prevent accidents ...
> 
> I guess busybox just doesn't do that which is the reason it is working there ...
> 
> I'll try to reproduce this locally and write a fix.  Can't promise I get it
> done today though ...
> 
> > But then works. In this case I see a kernel message (NOHZ:
> > local_softirq_pending) in between.
> > 
> > I run 4-5 times with -vvv, it works. The race is over with the traces :-(
> > 
> > Best regards,
> > Stefano



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