grabbing console (syscons) in kernel

[Andriy Gapon]

There are a few cases when the kernel needs to interact with a user via syscons.
This is the cases where the kernel not only spews some output but also expects
some input.  Some examples are:
- asking for a root filesystem specification
- entering ddb
- asking to press a key for reboot

In this cases the kernel implicitly grabs the console for its own use.
I'd like to make action more explicit.

What do you think about the approach and implementation in the following patches?
Thank you!

https://gitorious.org/~avg/freebsd/avgbsd/commit/5248b49ebf84d98a0597fa5aa4d813a38f581acc
https://gitorious.org/~avg/freebsd/avgbsd/commit/a0849c52242378474bb2eaa41726376fbc4c5bf6
https://gitorious.org/~avg/freebsd/avgbsd/commit/a67515cbd720b16f03ba435ed182966a8a338b15
https://gitorious.org/~avg/freebsd/avgbsd/commit/b8864b68b4c0e26ece065a38301c305833be32eb
https://gitorious.org/~avg/freebsd/avgbsd/commit/1017ae425d8abecd7482bd6c6deaaf9f25f5c6cd

P.S. one of the benefits is that a keyboard is put into and out of the polling
mode before getting all the required input and after that; not around each
character as it is done now in rather twisted way.

-- 
Andriy Gapon