Serial (was: patch for the commands chapter)

[Alessandro Rubini]

Disclaimer: I didn't try it out recently, my comments come from reading
the code.

>> There is a serious problem with "serial" in my opinion. Why does it
>> wait for user input?

(sorry, it was "terminal serial")

> Because the user may not run a terminal emulator, when GRUB starts up.

But the user may not run a local console when the "terminal" command
is executed from the configuration file. And if the user is
interactive and requests "terminal serial" without having a serial
connection it's user's fault.

Hmm... or is the "press any key" displayed to the serial console? If
so, things are less bad than they could be, but still bad. Why should
it stop there (and by default it stops for an infinite time) before
going on with its tasks?

Does the "halt" or "reboot" command ask to enter any key? Obviously
not. If the user fail in typing a command I don't care. If I don't
have a local console where to hit a key I *do* care, because the
functionality is not useable.

>   I disagree. Why shouldn't a serial terminal be treated differently?

Because a serial terminal is exactly like a local terminal: an I/O
channel. No difference at all (oh, sure, the driving code is different,
but programs are there to offer abstractions).

> Anyway, you can specify the timeout (even as zero), if you don't
> like the "policy".

>From my reading of the code, at timeout expiration GRUB resets the
default terminal. So setting the timeout to 0 means "no serial console".

BTW: the exchange of "speed" and "port" is from 2000/09/01, the
original bug was having two "port" and no "speed", but the fix was
incorrect (from cvs diff).

/alessandro