grub2 accessibility: beeps

[Hollis Blanchard <hollis@penguinppc.org>]

One topic that I've heard a lot about in the past few weeks is
accessibility in grub2. Blind users, who otherwise have various devices
like screen readers and brail TTYs, need to be able to interact with the
bootloader.

This can be as simple as using the PC speaker to beep when GRUB starts,
and also to beep differently (e.g. different pitch, or different number
of beeps) when highlighting different menu entries.

Thanks to Vincent, we already have a PC speaker driver (cool!). However,
we lack the ability to trigger it when switching menu entries (without
selecting one). The problem boils down to this:
        menuentry "foo" {
        	linux foo
        }

The commands inside the menuentry block are only executed when the entry
is selected, not highlighted. Perhaps the menuentry command could be
extended to take an optional beep argument:
        menuentry "foo" <pitch> <duration> {
        	linux foo
        }

But wouldn't it be better to have something more general? Something like
        menuentry {
        	title "foo"
        	beep pitch duration
        }
        {
        	linux foo
        }

Thoughts?

-Hollis