Bdtyktl

I've installed Ubuntu 14.04 on a mid 2010 iMac.

When I don't set the nomodeset kernel option I'm getting a black screen. It does actually boot because I can hear the login screen sound. The screen is just black.

If I enable nomodeset I'm not getting 3D acceleration using the open-source radeon drivers.

I'm sure its this one: http://support.apple.com/kb/sp588 (I'm not at work so I can't check it). And I'm also for 75% sure it has the "ATI Radeon HD 4670". I'm at least 100% sure its a 4xxx series.

I'm booting using whatever is Ubuntu's default but I'm sure its not EFI. I'm using rEFInd and I'm sure it says 'legacy OS'. So, not EFI.

Doing some further research, I have discovered that your graphics card no longer has drivers supported by ATI. Legacy downloads are also no longer available. And as such, X11 and the Linux Kernel do not support the legacy drivers, even if you were to get a copy elsewhere. In short, it will not work at all. nomodeset is, unfortunately, your best option.

There is another way however.

As linked in a comment, this answer might be able to help you. It will add a PPA where you can get the legacy driver. However, this is very risky and I do not recommend it at all. You will be downgrading you X11 and your kernel, which may break your entire system. Do not try it unless you really, really, really, really need the full ATI card power. Other posts in that thread might be able to help you, but back up your PC and be okay with re-installing from scratch.

<sup>If you do follow that answer, I am not responsible for any harm done to your computer. I have given you plenty of fair warning. Backup before even trying that. And do not blame me. I did not force you to try that.

Reason for Linkage: I do not condone following those steps. Consider it like a safeguard. Only view those instructions if you are okay with having to reinstall Ubuntu from scratch.</sup>

Finally, the open source driver appears not to work due to a bug. I suggest you try to seek help in that forum and maybe even comment that it isn't working for you.

Bug #597070 -- Updated 10/18/2014

Status: Fix-Released 8/15/2013

Importance: Medium

Assigned: No

I use a mid 2010 27" imac with Ubuntu and everytime (thus far) it has been a real pain to install due to the complicated limbo state of the graphics card support. With lots of 'nomodeset', rescue disk, editing x11 conf etc etc.

fglrx in this case is NOT a good idea, it simply does not work properly with 3d acceleration, neither does fglrx-legacy.

However, the most important thing to do, is make sure you are using the right installer. Use the 'mac alternative'. This (14.04.01) is the FIRST time, I have been able to do the whole installation using the GUI installer and be landed in an OS with properly working drivers with 3d acceleration using a 4xxx card (Mobility Radeon HD 4850 in my case).

So thanks ubuntu ! took a while but great.

Installer I used was : ubuntu-14.04.1-desktop-amd64+mac.iso

From UK mirror

http://www.mirrorservice.org/sites/cdimage.ubuntu.com/cdimage/releases/14.04.1/release/

The actual driver packaged with this is the Community driver as described here.

https://help.ubuntu.com/community/RadeonDriver

Hope that helps some one ( probably me next time I do it! ).

On the note of EFI and booting :
I use rEFIt, I have not had to change it for 4 years, I just reinstall over my previous linux partition. Your Linux partions should not be EFI, they should be Ext4 or something else, heres a print out of mine in case it helps.

bob@bob-iMac:~$ sudo parted /dev/sda print



Model: ATA ST31000528ASQ (scsi)

Disk /dev/sda: 1000GB

Sector size (logical/physical): 512B/512B

Partition Table: gpt



Number  Start   End     Size    File system     Name                  Flags

 1      20.5kB  210MB   210MB   fat32           EFI System Partition  boot

 2      210MB   100GB   100GB   hfsx            MAC

 3      100GB   300GB   200GB   ext4

 5      300GB   308GB   8000MB  linux-swap(v1)  swap

 6      308GB   1000GB  692GB   ext4            DATA

sda3 here is my main installation eg /

I've successfully installed a dual-booting Ubuntu 15.04 on a Mid 2010 21.5" iMac (model 11,2, with Radeon HD 4670) using rEFInd. I'd messed around with various permutation of nomodeset and friends and in the end removing the official (but misbehaving) ATI drivers was the step that allowed me to go back to a normally-booting, single-screen iMac. It Just Worked (tm). The steps, from memory, were:

1. Partition the disk to give Ubuntu some space to install


2. Install rEFInd


3. Burn the standard Ubuntu install DVD (iso -> cdr via Disk Utility. USB stick wasn't working for me)


4. Plug in an external monitor


5. Reboot and select the Ubuntu DVD to boot from the rEFInd menu


6. Once the Ubuntu desktop appears install it. I allowed it to auto-partition all free space.


7. Eject, reboot. Choose Ubuntu in the rEFInd menu.


8. 
   

   Once you've logged in the first thing to do is to remove the official radeon drivers:

   
   
   

   % sudo apt-get purge fglrx*

   
   



9. Shutdown



10. Unplug the external monitor


11. Power on. Hopefully you've now got a functioning Ubuntu installation that will work without a second screen.

Performance-wise it all seems quite nippy for a 5-year-old machine. Runs Windows 8 in VBox fine, handles Blender fluid sims at a reasonable pace etc. I've not tried gaming yet so can't comment on the 3D etc, but WFM.

If you want to use the accellerating radeon drivers, try the solution I described in the my answer this question: 14.04 gets black screen unless radeon.modeset=0 remotely turn on your backlight.

Actualy it does not seem a problem of the radeon X-driver more that there is a point in the boot-process where someone/-ting switches of the backlight. So my solution does not involve a visible console - if you switch to it from the from the window manager.