[vbox-dev] Cannot compile guest additions

[Dan Egli]

I'm using Vbox 6.1.16 r140961 (Qt5.6.2) to host a few Gentoo Linux 
boxes. On those boxes I have kernel 5.4.80. I tried to install the guest 
additions so that I could enable copy and paste and what not, but the 
compile failed. The log shows a bunch of undefined symbols:

ERROR: "ttm_bo_eviction_valuable" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_tt_fini" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_put" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_move_to_lru_tail" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_validate" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_init" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_add_to_lru" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_kmap" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_tt_init" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_dma_acc_size" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_init_mm" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_device_init" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_del_sub_from_lru" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_kunmap" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_device_release" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_manager_func" [/tmp/vbox.0/vboxvideo.ko] undefined!
ERROR: "ttm_bo_mmap" [/tmp/vbox.0/vboxvideo.ko] undefined!


What's causing this and is there an easy fix?

-- 
Dan Egli
 From my Test Server