i915 KMS interferes with nVidia card

[Ben Johnson <intel-gfx@geekamole.com>]

Greetings,

Sorry if I'm violating list etiquette in any way--the readme link to 
intellinuxgraphics.org no longer works.

My hardware:
Asrock Z77 Extreme4 with iGPU Multi-Monitor enabled. Primary graphics is 
set to PCIe but that doesn't make a difference.
i7 3770k / HD 4000
nVidia GTX 660 running nVidia's binary drivers v334.21, although 
multiple versions have the issue

My software:
Stable Gentoo with gentoo-sources-3.12.13, although multiple kernels 
have the issue

I am trying to use both the HD 4000 graphics and the nVidia card 
simultaneously in a single-seat multiple-X-server Zaphod scenario. I 
have another cheap nVidia card on order so I don't have any urgent need 
and maybe not any need at all to get this working with i915.

The Zaphod setup works fine with the exception of two problems that 
occur only when the i915 driver is loaded with modesetting enabled. 
I.e., not loading i915 or setting "nomodeset" or "i915.modeset=0" at 
boot resolves the issue, but does not allow the HD 4000 to be used. With 
i915 loaded normally:

1) The nVidia virtual terminals are messed up. They appear zoomed-in and 
don't update.
2) The nVidia card does not resume correctly from suspend-to-ram. It 
prints some errors to dmesg and either doesn't wake the monitor up, or 
doesn't ever show the X session again until I reboot.

I am a C programmer and I don't mind helping to fix this if it turns out 
to be relatively simple issue and my help is desired. Is this a known 
limitation, and does anyone have a clear idea what the problem is or 
where to look?

Thanks,
-Ben Johnson