[Intel-gfx] [PATCH] RFC hax: drm/i915: Kick out vga console

[Chris Wilson]

On Mon, Dec 16, 2013 at 06:07:14PM -0200, Paulo Zanoni wrote:
> 2013/12/16 Daniel Vetter <daniel at ffwll.ch>:
> > On Mon, Dec 16, 2013 at 05:19:25PM +0000, Chris Wilson wrote:
> >> Touching the VGA resources on an IVB EFI machine causes hard hangs when
> >> we then kick out the efifb. Ouch.
> 
> Please take a look at arch/x86/kernel/setup.c, at the end of function
> setup_arch:
> 
> #ifdef CONFIG_VT
> #if defined(CONFIG_VGA_CONSOLE)
>         if (!efi_enabled(EFI_BOOT) || (efi_mem_type(0xa0000) !=
> EFI_CONVENTIONAL_MEMORY))
>                 conswitchp = &vga_con;
> #elif defined(CONFIG_DUMMY_CONSOLE)
>         conswitchp = &dummy_con;
> #endif
> #endif
> 
> Shouldn't this code already be doing what you want on IVB? Perhaps we
> could improve it to do what you want?

Yes. I jumped to the wrong conclusion, and double checking after
uninstalling efifb we default to the dummy console.
 
> >>
> >> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> >
> > Like I've said on irc I think we want a select DUMMY_CONSOLE here, at
> > least if none of the core developers objects. And we also need this (or
> > something similar) to make Paulo happy, this should fix unclaimed register
> > disasters due to vgacon accessing the dead vga ranges when unloading our
> > driver on hsw while pc8/D3 is in effect.
> >
> > Paulo, can you please give this a spin - you need to make sure that
> > CONFIG_DUMMY_CONSOLE is set though, so that needs some magic.
> 
> I teste the patch, it does the required magic to solve the remaining problem :)

Care to write a real changelog describing the problem this actually
solves then?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre