Bug 726839 - Serial connection is broken after serial ports are detected
Summary: Serial connection is broken after serial ports are detected
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: kernel
Version: 6.1
Hardware: All
OS: Linux
high
high
Target Milestone: rc
: ---
Assignee: Prarit Bhargava
QA Contact: Red Hat Kernel QE team
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2011-07-29 22:19 UTC by David Kovalsky
Modified: 2014-03-31 23:46 UTC (History)
4 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2011-11-11 20:02:54 UTC
Target Upstream Version:


Attachments (Terms of Use)

Description David Kovalsky 2011-07-29 22:19:05 UTC
In RHEL5, I was used to adding console=ttyS0 to grub.conf (and removing rhdb and quiet) which allowed me to see all kernel, later boot messages and in the end the login prompt appeared. 

This got broken in RHEL6. 

grub config:
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
serial --unit=0 --speed=9600 --word=8 --parity=no --stop=1
terminal --timeout=5 console serial
hiddenmenu
title RHEL6 (2.6.32-171.el6.x86_64)
        root (hd0,0)
        kernel /vmlinuz-2.6.32-171.el6.x86_64 ro root=/dev/mapper/penny-rhel6 rd_LVM_LV=penny/rhel6 rd_NO_LUKS rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us nomodeset crashkernel=auto console=tty0 console=ttyS0,9600n1

I've made no other changes in /etc/init / /etc/sysconfig/init


Now when I boot, I see kernel messages all the way up to
...
ERST: Table is not found!
Non-volatile memory driver v1.3
Linux agpgart interface v0.103
crash memory driver: version 1.1
Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled

And here the output stops. I can wait forever, but nothing appears.

I also have a VGA monitor connected, where the output keeps going. 

To get to the serial console prompt, I need to reset/restart the modem. Which sucks for 2 reasons:
 - the immediate output is lost. In case the system hangs during the boot before the console is restarted I'm not going to see it
 - the reconnecting itself is not very user friendly


Is it possible to get the same behaviour as in RHEL5?

[root@penny ~]# rpm -q upstart kernel util-linux-ng
upstart-0.6.5-10.el6.x86_64
kernel-2.6.32-171.el6.x86_64
util-linux-ng-2.17.2-12.el6.x86_64

Comment 2 Prarit Bhargava 2011-08-05 13:59:30 UTC
David, what type of system is this?

P.

Comment 3 David Kovalsky 2011-08-05 14:18:27 UTC
Hey Prarit, 

it's an older user grade AMD system with ASUS mobo.

What kind of info are you interested in? Will lspcie + dmidecode give you enough info?

Comment 4 Prarit Bhargava 2011-08-10 18:41:24 UTC
Try console=ttyS0,9600n81 .

P.

Comment 5 David Kovalsky 2011-10-05 12:18:41 UTC
Hi Prarit, 

it seems it's not actually a problem on the server side, but on the client side - issue in the cheap USB <--> serial converter. Because if I connect directly via serial <--> serial it works fine. 


And JFTR -  console=ttyS0,9600n81 makes no difference in my case.


Note You need to log in before you can comment on or make changes to this bug.