Tech Source GFX 400 Series - Manual (Page 28)

GFX 400 Series Installation and Reference Manual
3-16
For example, if the GFX 400 device is located in slot 3, and the
secondary framebuffer is located in slot 1, then update the
pcia-probe-list
so that slot 3 is probed BEFORE slot 1.
A possible configuration may resemble the following:
ok setenv pcia-probe-list 3,2,1,4
ok reset-all
Once the system is reset, all console messages will be directed
to the GFX 400 card.