In message <20010105101405.E429@dr-evil.shagadelic.org>, Jason R Thorpe writes:
>If the system is in a state where you need to hit the BRS, what makes
>you think that the (software) console abort is going to do anything
>useful?

Experience.  If the process in the console window is wedged, and either
there's no network or the network is wedged, the kernel can still be in a
state where it can handle the console abort.

>Console abort is only useful if it's provided by the firmware on the
>system (i.e. Abort Switch on the AlphaServers, which traps into the
>firmware).  If you have to rely on the (wedged) operating system to
>provide the abort functionality, well ... that's not useful at all.

But in practice, it *is*.  There is a broad range of states where the OS
is functional enough to process keyboard interrupts, but not functional enough
to, say, let me kill the process that currently has my console window tied
up, or let me log in on another console.

It doesn't have to be useful very often to be worth having available.

-s