[RFC] Try a bit harder to get output on the screen at panic time

[James Simmons]

> On Fri, 9 Apr 2010 15:10:50 -0700
> Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> 
> > This set of 3 patches makes it a little more likely we'll get panic
> > output onto the screen even when X is running, assuming a KMS enabled
> > stack anyway.
> > 
> > It gets me from a blank or very sparsely populated black screen at
> > panic time, to one including the full backtrace and panic output at
> > panic time (tested with "echo c > /proc/sysrq-trigger" from an X
> > session).
> > 
> > It doesn't cover every case; for instance I think it'll fail when X has
> > disabled the display, but those cases need to be handled with separate
> > patches anyway (need to add atomic DPMS paths for instance).
> > 
> > Anyway, please test these out and let me know if they work for you.
> 
> Ping Linus & Dave again.  Have you guys tried these?  Really, it's cool.

Is this safe with UMS and vgacon/sticon? With a oops while using vgacon 
you can now touch the hardware buffer while not in vga text mode.