[rescue] SUMMARY: 7043-260 serial console help - no login prompt

Scott Mickey mickey at denver.net
Fri Aug 31 09:22:29 CDT 2007

Wise Rescuers, 
I'm now seeing a normal login prompt on the serial console (tty0). 
This was accomplished through software, not by building a new 
serial cable.  After about 20 years of dealing with the RS232 
"standard", I get very irritated, grumpy, and impatient every time 
I have to build a custom DB9 or DB25 connector for a specific 
machine.  So, I avoid it if at all possible. 
A *BIG* Thank You to Patrick Finnegan who sent me this single 
line AIX command: 
chdev -l tty0 -P -a runmodes=hupcl,cread,brkint,icrnl,opost,tab3,onlcr,isig,icanon,echo,echoe,echok,echoctl,echoke,imaxbel,iexten,clocal -a logmodes=hupcl,cread,echoe,cs8,clocal
While this command looks intimidating, it just sets the default 
behavior for tty0, plus adds "clocal" which means "without modem 
control".  Also, I added the -P.  Since tty0 is in use as the 
console, it's properties cannot be changed while the machine is 
running.   -P makes the changes effective after reboot. 
So I still have the same terminal server cables and connectors 
for all my machines (Sun, HP, IBM), and life is good. 
Scott Mickey 

On Thu, 30 Aug 2007, Patrick Finnegan wrote: 
> Run this (as all one line:)
> chdev -l tty0 -a 
> runmodes=hupcl,cread,brkint,icrnl,opost,tab3,onlcr,isig,icanon,echo,echoe,echok,echoctl,echoke,imaxbel,iexten,clocal
> -a logmodes=hupcl,cread,echoe,cs8,clocal
> I think that missing "clocal" on logmodes will make the system not even
> put up a login prompt if it's missing the right handshaking lines,
> which sounds like it's what your problem may be.
> Pat
> -- 
> Purdue University Research Computing ---  http://www.rcac.purdue.edu/
> The Computer Refuge                  ---  http://computer-refuge.org

On Thursday 30 August 2007, Scott Mickey wrote:
> Wise Rescuers,
> I have an IBM 7043-260 (headless), with a 9600-8-N-1 serial cable on
> tty0. Installation of AIX 5.2 goes fine using the serial console, and
> after install I am able to telnet into the box OK.  However, I get no
> login prompt on the serial cable console.
> The terminal server hardware I'm using works OK with all Sun SPARC
> and HP PA-RISC machines, and OK with the IBM 7043-260 during install.
> It appears the IBM serial port changes it's behavior after AIX 5.2
> boots. This web page says this is the case, anyway:
> http://www.linuxquestions.org/questions/showthread.php?t=314384
> I would like to have login access on the serial port ...

More information about the rescue mailing list