How to change back to the console when stucked by the desktop environment

[Michael B. Eichorn]

On Sun, 2016-07-17 at 16:36 +0800, Yubin Ruan wrote:	
> 
> Thanks, I just manage to install a proper desktop environment(Xfce)
> to 
> use and it seems to work fine.
> However, still, I cannot manage to do tty-switching using <Ctrl-
> Alt><F_> 
> (<Alt-F_> didn't work either). Strangely, whenever I press 
> <Ctrl-Alt><F_>, the whole desktop block. I don't know why, it just
> block 
> everytime I press <Ctrl-Alt><F_> ( the _ stand for number 1...8)
> 
> My /etc/ttys file looks like this:
> 
>      console     none                   unknown    off   secure
>      ttyv0    "/usr/libexec/getty Pc"   xterm      on    secure
>      .
>      .          (the same )
>      .
>      ttyv7    "/usr/libexec/getty Pc"   xterm      on    secure
>      ttyv8    "/usr/local/bin/xdm-nodaemon"  xterm  off  secure
> 
>      #serial terminal
>      ttyu0    "/usr/libexec/getty 3wire"   vt100   onifconsole secure
>      .
>      .
>      ttyu3    "/usr/libexec/getty 3wire"   vt100   onifconsole secure
> 
>      #Dumb console
>      dcons    "/usr/libexec/getty std.9600"  vt100 off  secure
> 
> Any idea?
> 
> Thanks,
> Ruan

Maybe it could be KMS related? Try swithing the console driver from
sc(4) to vt(4) by adding:

kern.vty=vt

to /boot/loader.conf and rebooting.

Vt(4), also known as newcons is the UTF-8 and KMS friendly console
driver. Vt(4) will be the console driver for 11.0 (r274085) but the
older sc(4) is the default on 10.x.