[BRLTTY] Starting brltty as early as possible.

[Jason White]

Just a quick follow-up question: in most distributions, if you boot into
single user mode, are the required device files guaranteed to be created, and
the required file systems mounted? I am thinking in particular of a UDEV-based
arrangement where most device files are created dynamically

I haven't tested this under Debian, but as I remember from years past, single
user mode performs basic initialization and then prompts for the root
password, at which point a root shell is available. Red Hat used to offer a
root shell without any password prompt, with the obvious security implications
for anyone with access to the boot loader.