Rusty Russell wrote:

If we make it thought early_fault, this will do just that.

Given this is a "never happens" situation, however... if you're actually
under Xen or lguest, you won't make it that far (lguest, at least, will
kill you on the cr2 load in early_fault, but it doesn't matter because
we won't get anywhere with early_printk anyway).

Actually, if we did BUG() here at least lguest would print something...
I wonder what Xen would do...

Xen would print a complete register dump and backtrace.  There's not a
lot else you can do here; you could try early_printk, but if we're in a
strange virtual environment, there may be no device on which the output
could appear.

    J