iMac11,1 (RV770/M98L [Mobility Radeon HD 4850]) needs nomodeset to boot
Submitted by Nicolas Jungers
Assigned to xf86-video-ati maintainers
Created attachment 127000
Xorg.log of a failed boot
My iMac11,1 was running Ubuntu since the beginning and till 14.04 fine but gave a black screen, with sometimes horizontal lines flowing since 15.04.
After applying the Apple patches Mac EFI Security Update 2015-002 (https://support.apple.com/kb/DL1848?locale=en_US) and 27-inch iMac SMC Firmware Update 1.0 (https://support.apple.com/kb/DL1030?locale=en_US), my iMac was unable to boot in graphical mode without the nomodeset kernel parameter.
Grub console is sluggish (but not for Ubuntu 11.10 and 12.04), sleep doesn't work and overall graphic performances are bad.
I had to install OSX El Capitan for flashing the iMac and I didn't have issues in OSX.
I join an Xorg.log of a failed boot (without nomodeset).
Attachment 127000, "Xorg.log of a failed boot":