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Background:

  • I perfectly installed Linux (dual-boot) on an iMac 2010 a couple of years ago.
  • Recently I spent hours to figure out why the iMac was not running "Target Display" mode under MacOs / OSX. Got it, it needs High Sierra or earlier (I incorrectly assumed High Sierra or newer).
  • More and more older iMacs are getting (somewhat) obsolete. That is a shame since we can really re-use them well, the screens are great (2560x1440), and with SSD they are very fast. I just hate to throw away good working hardware.

Question:

Can I boot the iMac in Linux and make it work in a kind of 'monitor mode' by using the Mini DisplayPort port?

I really want to connect via a cable, prefer not to mirror screen via WiFi etc, like the links supplied for example here.

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  • Did you find a solution for this? I am looking to do the same thing -- the accelerated graphics on the iMac is dead (has been revived by baking two times), but I would really like to use it as a display without having to tear out everything. Commented Mar 22, 2022 at 21:38
  • No, my workaround uses OSX, see below. Commented Jun 13, 2022 at 18:45

1 Answer 1

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I did not find an answer for this, but I did find a workaround. But that one is not Linux related. What I did: I decided to only use this iMac as an external monitor.

  1. I unplugged the mac from internet (disconnect eth0 cable and shut down WiFi too)
  2. I created a new user 'screen' with a simple password that I can type fast
  3. I configged that user to automatically log in (need to turn off FileVault for that)
  4. I connected an old keyboard to it

Now I just turn on the mac, it starts OSX High Sierra and logs in the user. Then I connect my laptop and I have a 'free' 27" screen, without hands! And a great screen too!

When shutting down, just press the start/shut-down button on the back of the Mac, and use the cheap keyboard to select 'shutdown'.

it also wakes up the iMac as external screen nicely

Personally, for me it really is an environmental choice. I mean, a 27" monitor is 180 euro or dollar or so, our company can afford that. But why buy a new monitor that is shipped all the way from China, uses costly material to produce, when the old screen is still good?

Reduce, reuse, recycle! Even though the iMac consumes ± 150 Watt / hour, it is better for the environment when you are using it not to much.

Hope this helps!

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  • What OS did your laptop have and what cable did you use to connect the two? Thank you for sharing your solution! Commented Dec 6, 2024 at 17:23
  • I was running OSX Montery and used an UCB-C cable connected to a DisplayPort (!!) USB-C adapter adapter from CableMatters. Yet, I believe in OSX Ventura Apple changes something, and it stopped working. Since early 2024 I believe I have not used it anymore. The iMac is now a Linux Zigbee sniffer :-) Commented Dec 9, 2024 at 17:04

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