[CentOS] CentOS7 - Serial Console and Flow Control

Thu Oct 15 19:54:18 UTC 2015
Lamar Owen <lowen at pari.edu>

On 10/15/2015 03:05 PM, Mike - st257 wrote:
> Would anyone be so kind as to share their experience?
> What has worked for your BMC/SoL configurations?
I have a C7 server with a physical RS-232 console, but the config should 
be similar.  I did not have to generate a systemd service for this; 
systemd saw the console line and automatically started the getty without 
me having to generate a .service file (as far as I recall all I had to 
do was generate the proper /etc/default/grub, and then run 
'grub2-mkconfig -o /boot/grub2/grub.cfg' and it Just Worked).

Now, I have the system set for console on both the VGA and on ttyS0, and 
I am not using flow-control.  Here's what I have that works (again with 
a physical ttyS0):

[root at backup670 ~]# cat /etc/default/grub
GRUB_SERIAL_COMMAND="serial --unit=0 --speed=9600 --word=8 --parity=no 
GRUB_TERMINAL_OUTPUT="console serial"
GRUB_CMDLINE_LINUX="rd.md.uuid=long-uuid-string crashkernel=auto 
rd.lvm.lv=vg/swap rd.lvm.lv=vg/root rd.md.uuid=another-long-uuid 
console=tty0 console=ttyS0,9600 rd_NO_PLYMOUTH"

Also see: http://0pointer.de/blog/projects/serial-console.html

There should be no need to modify any .service files; simply editing 
/etc/default/grub and regenerating grub2's config should be enough; it 
was in my case (I verified by looking through root's .bash_history and 
finding the lines around editing /etc/default/grub and not finding any 
edits of any .service files....)