[CentOS] CentOS7 - Serial Console and Flow Control

Thu Oct 15 19:05:36 UTC 2015
Mike - st257 <silvertip257 at gmail.com>

Hello List,

I'm ironing out details to upgrade a few systems to CentOS7.

My servers have BMC with Serial over LAN support. In C5 and C6, I
determined how to have BIOS/POST, kernel, and serial console access. I'm
reading up on the method to accomplish the pieces with C7.

Presently SoL output works, so I see BIOS/POST messages and the GRUB boot
My changes to enable serial redirection for the kernel do not appear to

I've made the following changes to GRUB2's /etc/grub/default config file:
-- removed rhgb
-- added the console= settings to GRUB_CMDLINE_LINUX
-- added  the last two lines related to serial as detailed here [0].

* Is there an option to enable hardware flow control?
I recall having to turn on flow control (agetty -h) to make it behave.
No mention of flow control at [1] or [2].
Nor does RHEL7 doc [3] mention it.

I've already tweaked the systemd service I generated for ttyS1 (I'm using
COM2 for SoL) and added the agetty "-h" option (for hardware flow control).
Despite modifying the baud rate to reflect the BMC's settings, I only get
symbols (so the console settings are amiss).

Would anyone be so kind as to share their experience?
What has worked for your BMC/SoL configurations?

[0] https://fedoraproject.org/wiki/GRUB_2#Enable_Serial_Console_in_Grub
[1] http://www.gnu.org/software/grub/manual/grub.html#Serial-terminal
[2] http://www.gnu.org/software/grub/manual/grub.html#serial
[4] https://lists.centos.org/pipermail/centos/2014-October/146719.html

//  SilverTip257  //