Help on DRI/DRM in Dell Inspiron 500m with i855GM chipset

[Vbman]

I used to be a RedHat owner and work well in Dell Inspiron 500m with i855GM chipset after installing the 855patch rpm.

However, I can't simply apply the rpm in Gentoo. I tried to install DRI, DRM and i810 drivers from Intel and also used the 855patch. I also emerged xfree-drm. But still the display cannot go up to 1024x768 16bit. Only 640x480 16bit or 800x600 256 are reachable.

Can anyone help me? Thank you very much!