kernelソースを利用するportsをリストアップしてみました。
kernelを更新したら以下の中でインストールされている物があれば再起動前に合わせて更新することをおすすめします。

audio/aureal-kmod
audio/oss
chinese/big5width
chinese/telnet
comms/hso-kmod
comms/ib-kmod
comms/uarduno
comms/uhso-kmod
comms/umcs7840
devel/linux_kdump
devel/linux-js
devel/linuxthreads
emulators/kqemu-kmod
emulators/kqemu-kmod-devel
emulators/parallels-tools
emulators/rtc
emulators/virtualbox-ose
emulators/virtualbox-ose-additions
emulators/virtualbox-ose-kmod
emulators/virtualbox-ose-kmod-legacy
emulators/virtualbox-ose-legacy
emulators/vmware-guestd4
emulators/vmware-guestd5
emulators/vmware-guestd6
graphics/kix-kmod
graphics/plasma-kmod
misc/dahdi-kmod
multimedia/cuse4bsd-kmod
multimedia/cx88
multimedia/linux_dvbwrapper-kmod
multimedia/linux_v4l2wrapper-kmod
multimedia/ptx-kmod
multimedia/pvr250
multimedia/pvrxxx
multimedia/pwcbsd
multimedia/sms1xxx-kmod
net-mgmt/ng_ipacct
net/acx100
net/asterisk-oh323
net/bwi-firmware-kmod
net/bwn-firmware-kmod
net/click
net/iet
net/ipvs
net/ipw-firmware
net/ipw-firmware-kmod
net/iwi-firmware
net/mpd4
net/mpd5
net/ng_car
net/ng_daphne
net/openafs
net/skyfish
net/skystar2
net/ttbudget
print/acroreadwrapper
security/quantis
security/quantis-kmod
sysutils/biosfont
sysutils/cciss_vol_status
sysutils/devcpu
sysutils/fusefs-kmod
sysutils/fusefs-sshfs
sysutils/graid5
sysutils/lsof
sysutils/mono-kmod
sysutils/pefs-kmod
sysutils/pmap
sysutils/scprotect
sysutils/uhidd
sysutils/vordog
textproc/gxditview
x11-drivers/input-wacom