gentoo에다가 nvidia 설치하려는데...

emerge nvidia-kernel
명령을 실행하면

localhost / # emerge nvidia-kernel
Calculating dependencies ...done!
>>> emerge (1 of 1) media-video/nvidia-kernel-1.0.6629 to /
x86
>>> md5 src_uri ;-) NVIDIA-Linux-x86-1.0-6629-pkg1.run
x86
x86
>>> Unpacking source...
 * /usr/src/linux is a symbolic link
 * Determining the real directory of the Linux kernel source code
 * Building for Linux 2.6.9 found in /usr/src/linux
Creating directory NVIDIA-Linux-x86-1.0-6629-pkg1
Verifying archive integrity... OK
Uncompressing NVIDIA Accelerated Graphics Driver for Linux-x86 1.0-6629.........................................................................................................................................................................................................
 * Applying conftest_koutput_includes.patch ...                           [ ok ] * Applying nv-pgd_offset.patch ...                                       [ ok ] * Applying nv-pgprot-speedup.patch ...                                   [ ok ] * Applying nv-vm_flags-no-VM_LOCKED.patch ...                            [ ok ] * Applying nv-disable-preempt-on-smp_processor_id.patch ...              [ ok ]x86
 * Applying nv-shutup-warnings.patch ...                                  [ ok ]>>> Source unpacked.
x86
 * Using /usr/src/linux as kernel output location

Your kernel was configured to include rivafb support!

The rivafb driver conflicts with the NVIDIA driver, please
reconfigure your kernel and *disable* rivafb support, then
try installing the NVIDIA kernel module again.

*** Failed rivafb sanity check. Bailing out! ***

make[1]: *** [rivafb-sanity-check] 오류 1
make: *** [module] 오류 2

!!! ERROR: media-video/nvidia-kernel-1.0.6629 failed.
!!! Function src_compile, Line 147, Exitcode 2
!!! Failed to build module
!!! If you need support, post the topmost build error, NOT this status message.

이런 오류를 내면서 설치가 되지 않습니다.
이유를 전혀 모르겠습니다. 빠른답변 부탁드립니다..