[PATCH] failsafe: run on all consoles listed in /proc/cmdline

[Nathan Lutchansky]

On Sun, 5 Jun 2022, Mark Mentovai wrote:

> By running shells on all consoles listed in /proc/cmdline, failsafe mode
> will work correctly on devices with a serial console (like apu2), and
> the same image without any need for reconfiguration can be shared by
> devices with the more traditional (for x86) VGA console.

More generally, this is probably worth digging into further to figure out 
how to achieve consistency on platforms with both a local display and a 
primary serial port that are equally likely to be used as the main 
console.  For example, on a Raspberry Pi, the initial prompt to enter 
failsafe is only sent to /proc/console, which is the VGA console, not 
ttyS0.  -Nathan