Enabling the Installation USB Stick to Boot into a Serial Console

By default, booting into the USB stick boots into the installer. To instead boot into a serial console, mount the USB disk onto a FreeBSD system using mount(8):

# mount /dev/da0a /mnt

Once the USB stick is mounted, set it to boot into a serial console. Add this line to /boot/loader.conf on the USB stick:

# echo 'console="comconsole"' >> /mnt/boot/loader.conf

Now that the USB is stick configured correctly, unmount the disk using umount(8):

# umount /mnt

Now, unplug the USB stick and jump directly to the third step of this procedure.

Enabling the Installation CD/DVD to Boot into a Serial Console

By default, when booting into the installation CD/DVD, FreeBSD boots into its normal install mode. To instead boot into a serial console, extract, modify, and regenerate the ISO image before burning it to the CD/DVD media.

From the FreeBSD system with the saved installation ISO image, use tar(1) to extract all the files:

# mkdir /path/to/headless-iso
# tar -C /path/to/headless-iso -pxvf FreeBSD-10.2-RELEASE-i386-disc1.iso

Next, set the installation media to boot into a serial console. Add this line to the /boot/loader.conf of the extracted ISO image:

# echo 'console="comconsole"' >> /path/to/headless-iso/boot/loader.conf

Then, create a new ISO image from the modified tree. This example uses mkisofs(8) from the sysutils/cdrtools package or port:

# mkisofs -v -b boot/cdboot -no-emul-boot -r -J -V "Headless_install" \
	    -o Headless-FreeBSD-9.3-RELEASE-i386-disc1.iso /path/to/headless-iso

Now that the ISO image is configured correctly, burn it to a CD/DVD media using a burning application.

Connecting the Null-modem Cable

Connect a null-modem cable to the serial ports of the two machines. A normal serial cable will not work. A null-modem cable is required.

Booting Up for the Install

It is now time to go ahead and start the install. Plug in the USB stick or insert the CD/DVD media in the headless install machine and power it on.

Connecting to the Headless Machine

Next, connect to that machine with cu(1):

# cu -l /dev/cuau0