On Yosemite (using Ozmosis and MacPro3,1 on a GA-Z87X-OC) I added the ID and everything is fine so far with my R290 as long as I have one display connected to DP only. If I connect one to DVI I have a crash during boot (black screen).
So I thought I have to create a proper frame buffer for the inputs. As per default RadeonFramebuffer is used. Googled a bit how to construct one.
I came up with this one, patched the kext and forced Baladi to be used as a Framebuffer (only one present in AMD8000Controller)
ATOM BIOS Rom:
SubsystemVendorID: 0x174b SubsystemID: 0xe285
BIOS Bootup Message:
C67111 Hawaii PRO OC GDDR5 4GB 64Mx32 300e/150m
PCI ID: 1002:67b1
Connector at index 0
Type [@offset 43540]: DisplayPort (10)
Encoder [@offset 43544]: INTERNAL_UNIPHY2 (0x21)
i2cid [@offset 43632]: 0x90, OSX senseid: 0x1
Connector at index 1
Type [@offset 43550]: HDMI-A (11)
Encoder [@offset 43554]: INTERNAL_UNIPHY2 (0x21)
i2cid [@offset 43659]: 0x92, OSX senseid: 0x3
Connector at index 2
Type [@offset 43560]: DVI-D (3)
Encoder [@offset 43564]: INTERNAL_UNIPHY1 (0x20)
i2cid [@offset 43686]: 0x93, OSX senseid: 0x4
Connector at index 3
Type [@offset 43570]: DVI-D (3)
Encoder [@offset 43574]: INTERNAL_UNIPHY (0x1e)
i2cid [@offset 43713]: 0x95, OSX senseid: 0x6
Framebuffer I created from these infos:
00 04 00 00 04 03 00 00 00 01 00 00 12 04 01 01
00 08 00 00 04 02 00 00 00 01 00 00 22 05 02 03
04 00 00 00 14 02 00 00 00 01 00 00 11 02 03 04
04 00 00 00 14 02 00 00 00 01 00 00 10 00 04 06
Well does not work even if I only connect one display to DP, black screen during boot.
During my first tries I had it working just after adding the ID, by removing my display port connection, re-plugging it and then plugging in the 2nd display into a HDMI port while Yosemite was still running.
I went away, and when a display went to sleep Yosemite crashed. On reboot I had a black screen from there on and couldn't reproduce it.
So anyone got this figured out how to run multiple displays on a R290? I saw some youtube videos where ppl. were doing it for an R290X with a similar frame buffer (using the last DVIs as the first two) but no real instructions I can work with. As the R290X and R290 are basically identical connection wise it should be doable.