mountroot issues (was Re: 10.0-release proposed patch for Atmel)

[John-Mark Gurney]

Warner Losh wrote this message on Sat, Dec 21, 2013 at 23:44 -0700:
> Right now, the mountroot prompt doesn't work on Atmel CPUs. Almost all the characters are eaten. I recently committed an elegant fix for this into head to mask the interrupt for new characters and only do polling.

So, a similar issue plages i386/amd64 too.  There the console mostly
works, but it will drop characters on occasion...  The problem is that
mount root spins calling into the console code instead of asking the
console code for a single character and having the console code wait
for this character...  and if you type a character while it's outside
the console routines, that character will be dropped...

The problem is, not many of us spend time at the mountroot prompt, and
so even if we notice the issue, it's so minor that we just deal w/
it...

The method I came up with years ago was to add a routine/flag that would
have the console wait for a character instead of simply returning when
there was no character...  Though if we implement cngrab properly where
we don't flush buffers, turn off interupts, etc, then that would work
too...

I've cc'd -arch since it's not just an -arm issue.

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."