# Linux issues on iMac

I have Ubuntu 18.04.4 LTS and Arch Linux installed on 
an iMac, which I think doesn't support KMS. I have gotten Ubuntu to work with several desktops, window managers, and display managers. When I attempted to install Manjaro, nothing worked, even with `nomodeset`, so I tried Arch. I have gotten the TTYs to work on Arch, but not X (I haven't tried Wayland yet). The problems I have had so far:

- Booting without `nomodeset` results in a black unresponsive screen
- I can't successfully `startx` or `xinit` on Arch even with `nomodeset`
- Suspending in Ubuntu results in a black unresponsive screen
- Ubuntu brightness keys don't work, but an image on the screen says it does

I have a bunch of information, please let me know if any is unnecessary, or if I need to add more details.

## More boot info

When I boot without `nomodeset` I see some info ending with the following:

```
*Error* No UMS support in radeon module!
```

At this point, the resolution sharpens slightly, then the screen goes black. With `nomodeset`, the screen doesn't go black but shows more logs, then proceeds to the login screen.

UPDATE: I used to be able to see that message, but I can't seem to bring it back. Everything else is the same, though.

## Ubuntu 18.04

System info (as found in settings GUI):

- Memory: 3.8 GiB
- Processor: Intel® Core™️ i3 CPU 540 @ 3.07GHz x 4
- Graphics: llvmpipe (LLVM 9.0, 128 bits)
- GNOME: 3.28.2
- OS type: 64-bit
- Disk: 376.9 GB

`lspci | grep VGA` prints `01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RV730/M96-XT [Mobility Radeon HD 4670]`

`cat /var/log/Xorg.0.log` prints a whole bunch of stuff, let me know if you need any of it.

## Arch

`startx &` prints:

```
X.Org X Server 1.20.8
X Protocol Version 11, Revision 0
Build Operating System: Linux Arch Linux
Current Operating System: Linux amc-arch 5.6.5-arch3-1 #1 SMP PREEMPT Sun, 19, Apr 2-2- 13:14:25 +0000 x86_64
Kernel command line: BOOT_IMAGE=/boot/vmlinuz-linux root=/dev/sda3 nomodeset
Build Date: 30 March 2020 05:05:45AM

Current version of pixman: 0.38.4
 before reporting problems, check http://wiki.x.org
 to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
 (++) from command line, (!!) notice, (II) informational,
 (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file:"/var/log/Xorg.0.log", Time: Mon Apr 20 19:53:22 2020
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
ile at "/var/log/Xorg.0.log" for additional information.(EE) (EE) Server terminated with error (1). Closing log file.
xinit: giving up
xinit: unable to connect to X server: Connection refused
xinit: server error
Job 1, 'startx &' has ended
```

The log file is smaller, but still big. Let me know if it is necessary.

# KMS - Kernel Mode Setting

I have looked around the internet, and I believe the issue is kernel mode setting. If you know about this, I would appreciate help. Is the only solution an external graphics card that supports KMS? Can I use or make a window manager or desktop environment that doesn't require KMS? Can I make a suggestion to the Linux Kernel to make an alternative to KMS that will still work?

Why does Ubuntu work (mostly) but Manjaro doesn't?