misc/188549: Improve installation on serial console

[Anselm Strauss]

>Number:         188549
>Category:       misc
>Synopsis:       Improve installation on serial console
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sun Apr 13 10:40:00 UTC 2014
>Closed-Date:
>Last-Modified:
>Originator:     Anselm Strauss
>Release:        10.0-RELEASE-p1
>Organization:
>Environment:
FreeBSD heman 10.0-RELEASE-p1 FreeBSD 10.0-RELEASE-p1 #0: Tue Apr  8 06:45:06 UTC 2014     root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC  amd64
>Description:
I have a PC Engines APU platform that has no video console but only a serial one. Although there is a brief documentation in the handbook on how to get the installation image working on the serial console (https://www.freebsd.org/doc/handbook/install-advanced.html) a lot of things are missing or troublesome to get a properly working system manageable over the serial console only:

- Installation images have to be modified by hand to get serial console support
- Serial console is not enabled in the installed system, making it unusable for me
- Booting the installation image again and entering the rescue shell gives me no easy way to mount the installed system if it is on ZFS. Importing/exporting the pool is not very intuitive.
- Enabling SSHD during installation is an option. Later you can login over network and fix the serial console. But this relies on configuring a non-root user during installation and giving him the wheel group, otherwise you can not become root on the installed system over SSH.
>How-To-Repeat:
- Install fresh system on hardware with serial console support, put root on ZFS and enable SSHD
- Boot into the installed system, check serial console login
- Reboot to rescue shell, try configuring serial console
- Try logging in via SSHD, becoming root and configuring serial console
>Fix:
- Provide pre-built installation images with serial console support
- Provide option in installer to enable serial console on installed system
- Provide documentation on how to fix a system on ZFS with the rescue shell
- Provide option/documentation on how to configure user(s) to be able to fix installed system via SSH

>Release-Note:
>Audit-Trail:
>Unformatted: