I have after pulling teeth and hair installed Xubuntu 18.04 LTS on 2006 iMac 5,1 (ATI X1600 graphics).
I had to insert "nomodeset" in the installer to get graphics and complete installation. I have no other OS installed.
Now after installation, there are no graphics visible. I have removed "quiet" and inserted "nomodeset" and still no graphics are visible. Recovery mode options in GRUB also produce no graphics.
I have tried entering "echo" lines in grub after the images are loaded and can see those prints. Also, the HDD is all a flurry so boot is occurring, just no display.
It also is rejecting SSH connections so I am really stuck on how to get more information from the box as to what is going wrong.
EDIT: By blindly typing after Ctrl+Alt+F1 I have successfully got SSH installed so I can meddle with the box now.
FYI:
/var/log$ lspci -k | grep -EA2 'VGA|3D'
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RV530/M56-P [Mobility Radeon X1600]
Subsystem: Apple Inc. MacBook Pro
Kernel modules: radeon
nomodeset is being obeyed, but still no graphics, not even console prints:
Apr 17 13:38:37 macbuntu kernel: [ 17.486412] [drm] VGACON disable radeon kernel modesetting.
Apr 17 13:38:37 macbuntu kernel: [ 17.486456] [drm:radeon_init [radeon]] *ERROR* No UMS support in radeon module!
Here are the prints when left to boot normally:
Apr 17 14:11:18 macbuntu kernel: [ 19.829088] [drm] radeon kernel modesetting enabled.
Apr 17 14:11:18 macbuntu kernel: [ 19.829180] radeon 0000:01:00.0: remove_conflicting_pci_framebuffers: bar 0: 0x40000000 -> 0x47ffffff
Apr 17 14:11:18 macbuntu kernel: [ 19.829182] radeon 0000:01:00.0: remove_conflicting_pci_framebuffers: bar 2: 0x48400000 -> 0x4840ffff
Apr 17 14:11:18 macbuntu kernel: [ 19.829185] radeon 0000:01:00.0: vgaarb: deactivate vga console
Apr 17 14:11:18 macbuntu kernel: [ 19.829547] [drm] initializing kernel modesetting (RV530 0x1002:0x71C5 0x106B:0x0080 0x00).
Apr 17 14:11:18 macbuntu kernel: [ 19.829594] radeon 0000:01:00.0: Invalid PCI ROM header signature: expecting 0xaa55, got 0xa3a3
Apr 17 14:11:18 macbuntu kernel: [ 19.829616] radeon 0000:01:00.0: Invalid PCI ROM header signature: expecting 0xaa55, got 0x2323
Apr 17 14:11:18 macbuntu kernel: [ 19.829668] [drm:radeon_get_bios [radeon]] *ERROR* Unable to locate a BIOS ROM
Apr 17 14:11:18 macbuntu kernel: [ 19.829672] radeon 0000:01:00.0: Fatal error during GPU init
Apr 17 14:11:18 macbuntu kernel: [ 19.829675] [drm] radeon: finishing device.
Apr 17 14:11:18 macbuntu kernel: [ 19.829676] [TTM] Memory type 2 has not been initialized
Apr 17 14:11:18 macbuntu kernel: [ 19.829680] [drm] radeon: cp finalized