Re: [Xen-users] xenconsole: Could not open tty

[Sarah Newman <srn@xxxxxxxxx>]

On 04/29/2015 02:20 AM, Neech Worthington wrote:
> I have a problem with a guest VM that has broken mount point in its fstab, so 
> I'm trying to boot a guest in to single user mode with this:
> 
> xl create -c myguest.pv 'extra="single"'
> 
> (I've also tried just editing the grub kernel command line and suffixing 
> single or 1 or S on the end, and using the recovery console grub menu option
> instead, but every time I get the same outcome as below).
> 
> I see the grub screen okay, but once it has passed the timeout and starts to 
> boot the kernel, I get the following message send to my terminal:
> 
> --- 8< ---
> xenconsole: Could not open tty `': No such file or directory
> libxl: error: libxl_exec.c:118:libxl_report_child_exitstatus: console child 
> [0] exited with error status 2
> --- 8< ---
> 
> A few seconds later I do get output on my terminal again, but the console 
> does not appear to accept any of my inputs to press either S or M as per the
> prompting output:
> 
> --- 8< ---
>  * Starting set console font                                             [ OK 
> ]
>  * Stopping set console font                                             [ OK 
> ]
>  * Starting userspace bootsplash                                         [ OK 
> ]
> An error occurred while mounting /var/lib/munin.
> keys:Press S to skip mounting or M for manual recovery
>  * Stopping userspace bootsplash                                         [ OK 
> ]
>  * Starting Send an event to indicate plymouth is up                     [ OK 
> ]
>  * Stopping Send an event to indicate plymouth is up                     [ OK 
> ]
> --- 8< ---
> 
> So, I have a couple of questions.
> 
> 1. What is causing this xenconsole: Could not open tty error? How do I fix 
> it? Is it related to me not being able to type input in to my guest VM
> console after grub?
I would assume that 'extra="single"' is replacing your other kernel command 
line options.

> 
> 2. How on earth do I successfully get a single user mode boot on this guest 
> VM so that I can correct its fstab and get it to boot properly?

I am not 100% certain but I think that ubuntu doesn't configure a serial 
console getty by default if you did an install via another method. You might
be able to fix things by adding 'init=/bin/sh' to the kernel command line and 
then using 'mount -o remount,rw /' before trying to edit /etc/fstab.
Afterwards you'll want to follow something like 
https://help.ubuntu.com/community/SerialConsoleHowto for hvc0 instead of ttyS0.



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