titan ~ # emerge linux-uvc
Calculating dependencies... done!

>>> Emerging (1 of 1) media-video/linux-uvc-0.0.1_pre51 to /
>>> Downloading 'http://distfiles.gentoo.org/distfiles/linux-uvc-0.0.1_pre51.tar.bz2'
--13:55:13--  http://distfiles.gentoo.org/distfiles/linux-uvc-0.0.1_pre51.tar.bz2
           => `/usr/portage/distfiles/linux-uvc-0.0.1_pre51.tar.bz2'
Resolving distfiles.gentoo.org... 216.165.129.135, 156.56.247.195, 64.50.238.52, ...
Connecting to distfiles.gentoo.org|216.165.129.135|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 25,114 (25K) [application/x-tar]

100%[====================================>] 25,114        --.--K/s

13:55:13 (216.09 KB/s) - `/usr/portage/distfiles/linux-uvc-0.0.1_pre51.tar.bz2' saved [25114/25114]

 * checking ebuild checksums ;-) ...                                      [ ok ]
 * checking auxfile checksums ;-) ...                                     [ ok ]
 * checking miscfile checksums ;-) ...                                    [ ok ]
 * checking linux-uvc-0.0.1_pre51.tar.bz2 ;-) ...                         [ ok ]
 * Determining the location of the kernel source code
 * Found kernel source directory:
 *     /usr/src/linux
 * Found sources for kernel version:
 *     2.6.19-gentoo-r4
 * Checking for suitable kernel configuration options...                  [ ok ]
>>> Unpacking source...
>>> Unpacking linux-uvc-0.0.1_pre51.tar.bz2 to /var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work
 * Applying uvc-2.6.18.diff ...                                           [ ok ]
>>> Source unpacked.
>>> Compiling source in /var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51 ...
 * Preparing uvcvideo module
Building USB Video Class driver...
make[1]: warning: jobserver unavailable: using -j1.  Add `+' to parent make rule.

  WARNING: Symbol version dump /usr/src/linux-2.6.19-gentoo-r4/Module.symvers
           is missing; modules will have no dependencies and modversions.

In file included from /var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/uvcvideo.c:49:
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:8: error: nested redefinition of ‘enum v4l2_frmsizetypes’
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:8: error: redeclaration of ‘enum v4l2_frmsizetypes’
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:9: error: redeclaration of enumerator ‘V4L2_FRMSIZE_TYPE_DISCRETE’
include/linux/videodev2.h:286: error: previous definition of ‘V4L2_FRMSIZE_TYPE_DISCRETE’ was here
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:10: error: redeclaration of enumerator ‘V4L2_FRMSIZE_TYPE_CONTINUOUS’
include/linux/videodev2.h:287: error: previous definition of ‘V4L2_FRMSIZE_TYPE_CONTINUOUS’ was here
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:11: error: redeclaration of enumerator ‘V4L2_FRMSIZE_TYPE_STEPWISE’
include/linux/videodev2.h:288: error: previous definition of ‘V4L2_FRMSIZE_TYPE_STEPWISE’ was here
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:14: error: nested redefinition of ‘enum v4l2_frmivaltypes’
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:14: error: redeclaration of ‘enum v4l2_frmivaltypes’
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:15: error: redeclaration of enumerator ‘V4L2_FRMIVAL_TYPE_DISCRETE’
include/linux/videodev2.h:326: error: previous definition of ‘V4L2_FRMIVAL_TYPE_DISCRETE’ was here
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:16: error: redeclaration of enumerator ‘V4L2_FRMIVAL_TYPE_CONTINUOUS’
include/linux/videodev2.h:327: error: previous definition of ‘V4L2_FRMIVAL_TYPE_CONTINUOUS’ was here
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:17: error: redeclaration of enumerator ‘V4L2_FRMIVAL_TYPE_STEPWISE’
include/linux/videodev2.h:328: error: previous definition of ‘V4L2_FRMIVAL_TYPE_STEPWISE’ was here
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:24: error: redefinition of ‘struct v4l2_frmsize_discrete’
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:32: error: redefinition of ‘struct v4l2_frmsize_stepwise’
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:52: error: redefinition of ‘struct v4l2_frmsizeenum’
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:73: error: redefinition of ‘struct v4l2_frmival_stepwise’
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:84: error: redefinition of ‘struct v4l2_frmivalenum’
In file included from /var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/uvcvideo.c:49:
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:116:1: warning: "VIDIOC_ENUM_FRAMESIZES" redefined
In file included from include/linux/videodev.h:15,
                 from /var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/uvcvideo.c:38:
include/linux/videodev2.h:1329:1: warning: this is the location of the previous definition
In file included from /var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/uvcvideo.c:49:
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/v4l2_enumfrmfmt.h:117:1: warning: "VIDIOC_ENUM_FRAMEINTERVALS" redefined
In file included from include/linux/videodev.h:15,
                 from /var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/uvcvideo.c:38:
include/linux/videodev2.h:1330:1: warning: this is the location of the previous definition
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/uvcvideo.c: In function ‘uvc_init_isoc’:
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/uvcvideo.c:1558: warning: assignment from incompatible pointer type
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/uvcvideo.c: In function ‘uvc_init_status’:
/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/uvcvideo.c:3761: warning: passing argument 6 of ‘usb_fill_int_urb’ from incompatible pointer type
make[2]: *** [/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51/uvcvideo.o] Error 1
make[1]: *** [_module_/var/tmp/portage/media-video/linux-uvc-0.0.1_pre51/work/linux-uvc-0.0.1_pre51] Error 2
make: *** [uvcvideo] Error 2

!!! ERROR: media-video/linux-uvc-0.0.1_pre51 failed.
Call stack:
  ebuild.sh, line 1564:   Called dyn_compile
  ebuild.sh, line 937:   Called src_compile
  linux-uvc-0.0.1_pre51.ebuild, line 46:   Called linux-mod_src_compile
  linux-mod.eclass, line 482:   Called die

!!! Unable to make  KERNEL_DIR=/usr/src/linux uvcvideo.
!!! If you need support, post the topmost build error, and the call stack if relevant.