Hi All,
my first post here. Just wanted to share my experience on setting up Manjaro (Gnome) on my iMac. All in all iMac is very well usable, no osx is “missed” 
Here my 2cents 
What I have:
- iMac (with HighSierra) + firewire hd + sdxc card (64gb, class UHS 1).
- Wifi 5ghz via TpLink AP RE300 (more on this later) as repeater
- Manjaro is installed on the sdxc card
- Swap in a partition on the firewire disk. Reason: if crash/freeze/hard power off, and swapfile on a mounted partition, partition gets “corrupted” and subsequente reboot would not swapon swapfile, as partition would need a fsck
Issues solved (majority looking here in Manjaro or Arcwiki or googling):
-
Experience: If I connect on RE300, random access to Internet. Some website can be accessed, some other no. If I connect with wifi router all is fine.
Solution: enable NetworkManager to use an alternate dhcp client. I installed dhclient and set it in /etc/NetworkManager/conf.d/dhclient.conf -
Experience: no 5ghz band/network visible.
Solution: I live in Germany. I had to enable “DE” in wireless-regdom in /etc/conf.d -
Experience: Nightlight seems not working
Solution: I wrongly disabled “Laptop screen” in Setting/Color -
Experience: Magic keyboard/mouse need bluetooth reassignement after each OS is booted
Solution: See procedure mentioned in Arcwiki about bluetooth keyboard -
Experience: bluetooth headset “cracking” sound.
Solution: go with pipewire
Open Issues:
- Magic Mouse now and then “freeze”. I need to reclick and wait a moment to have it back working
- Some glitch/corruption on display where mouse pointer is. Especially at start up
- VPN does not automatic connect at boot
- TLP Gui has a defect (sub window to set up disks value does not open after initial install(
- Disks are starting/stopping too frequently (linked to tlp config I assume)
- Check iMac power usage/standby (to avoid daily power off/power on cycles)