Can I enable crossfire on Ubuntu 14.04?

Question

How can I enable crossfire mode on Ubuntu 14?

Graphics: 2 x AMD Radeon HD7790. Mainboard ASUS P5KC. OS: KUbuntu 14.04 x64.

aticonfig reports:

aticonfig --lscs
    Candidate Combination: 
    Master: 1:0:0 
    Slave: 4:0:0 
    CrossFire is disabled on current device
    CrossFire Diagnostics:
    CrossFire can work with P2P mapping through GART
    Dongle Capabilities: support PASSTHROUGH |INTERLINK_SW_AFR | INTERLINK_AUTO_AFR | INTERLINK_BLACKING | INTERLINK_SUPERAA

Answer 1

i do not know your motherboard ,so 1st step is to check if you have IOMMU and if is disabled

lspci | grep "IOMMU"

if it is disabled(prefer in bios) or your motherboard do not have it,then we need to make crossfire chain

aticonfig --cfa --adapter=0,1

and then just type

aticonfig --cf on --adapter=0

then we check crossfire status with

aticonfig --lscs

If you get message that is enabled then you can proceed to some bench to actually see benefit.

Most cards 99% still need crossfire link (bridge)... Do not forget that one to attach between cards.