Date: Fri, 12 Jul 2013 14:29:51 GMT From: Andrew Wright <ahamiltonwright@mta.ca> To: freebsd-gnats-submit@FreeBSD.org Subject: docs/180493: Single-user mode console confusion Message-ID: <201307121429.r6CETp8A019323@oldred.freebsd.org> Resent-Message-ID: <201307121430.r6CEU0J5018794@freefall.freebsd.org>
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>Number: 180493 >Category: docs >Synopsis: Single-user mode console confusion >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-doc >State: open >Quarter: >Keywords: >Date-Required: >Class: doc-bug >Submitter-Id: current-users >Arrival-Date: Fri Jul 12 14:30:00 UTC 2013 >Closed-Date: >Last-Modified: >Originator: Andrew Wright >Release: 9.1-RELEASE-p4 >Organization: Mount Allison University >Environment: FreeBSD qemg.org 9.1-RELEASE-p4 FreeBSD 9.1-RELEASE-p4 #0: Mon Jun 17 11:42:37 UTC 2013 root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC amd64 >Description: I have these lines in /boot/loader.conf in order to enable a sometimes-installed serial console device: boot_multicons="YES" boot_serial="YES" comconsole_speed="19200" console="comconsole,vidconsole" A side effect of these lines is that entering single-user mode produces a prompt only on the external console. This was extremely confusing when attempting to boot single-user, as all messages prior to the single-user prompt are produced on the vid terminal (and on the external console), however at the moment that single-user mode is entered, the mirroring ceases. While it is now clear what happened, the effect is that single-user mode appears to be unavailable. I have no /boot.config file that would indicate which console is meant to be used for messages. >How-To-Repeat: Add these lines to /boot/loader.conf, attempt to boot single user. >Fix: I would suggest adding some text to the handbook page "Setting up the Serial Console" http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/serialconsole-setup.html#serialconsole-loader Currently, these page makes no comment regarding single-user mode whatsoever. Informing the user that configuring the console may well have repercussions on entry to single-user mode will lessen confusion in the future. I would therefore suggest adding the following text into section 26.6.6 "Setting up the Console from the Boot Loader", subsection 26.6.6.1 "Setting Up the Serial Console": Note that entry to single-user mode will only honour input on one console, even if multiple consoles are indicated using the <tt>console</tt> boot option. Care must be taken that the first named console is available to the system manager entering single-user mode. I will note that the first sentence in this section "The boot loader and the kernel to use the serial console can be specified by writing one line in /boot/loader.conf" seems very poorly written -- I do not understand what this line is attempting to say. Additionally, there is already a section "26.6.7 Caveats"; a note here indicating possible effects on single-user boot would probably not go amiss. >Release-Note: >Audit-Trail: >Unformatted:
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