## System details

Apple iMac20,1 (Retina 5K, 27-inch, 2020), board Mac-CFF7D910A743CAAF; Intel Core i5-10600; AMD Radeon Pro 5300 only (Navi 14, `1002:7340`, Apple subsystem `106b:0219`, no Intel display adapter); Omarchy 4.0.4-1; kernel `7.2.6-arch2-Watanare-T2-1-t2`; LUKS + Limine + UKI. Debug log: https://logs.omarchy.org/0jLpvg

## What's wrong?

Omarchy's T2 installer path works for this machine's **keyboard, Wi-Fi, audio, fans, and storage**. It does **not** handle the **5K AMD display**, so a stock install does not boot to a usable LUKS prompt or desktop. The next person who puts Omarchy on a 2020 27" iMac will hit the same wall and have to edit the Limine `linux-t2` line by hand (`e`) on every boot unless they persist flags themselves.

This is a 27" T2 iMac with an AMD-only panel. `install/hardware/apple/fix-t2.sh` detects the T2 PCI IDs and installs `linux-t2`, firmware, `t2fanrd`, and:

```
KERNEL_CMDLINE[default]+=" intel_iommu=on iommu=pt pm_async=off mem_sleep_default=deep"
```

That is the documented T2 MacBook path. The [Mac support](https://omarchy.org/manual/mac-support/) T2 device list also does not include iMac20,1 / iMac20,2.

### Repro (fresh install, no extra flags)

1. Install Omarchy 4.0.4 on an iMac20,1 with the default encrypted setup.
2. Reboot into `linux-t2` with the stock cmdline (`quiet splash` + Plymouth + `kms` in the initramfs).
3. `amdgpu` takes over the EFI framebuffer, then SMU init fails. Screen goes black. LUKS prompt is not visible.

Kernel log from that boot (reproduced twice):

```
amdgpu 0000:03:00.0: initializing kernel modesetting (NAVI14 0x1002:0x7340 0x106B:0x0219 0x47).
amdgpu 0000:03:00.0: Fetched VBIOS from VFCT
amdgpu 0000:03:00.0: [drm] ATOM BIOS: 113-D322A1XL-011, build: 521467  , ver: 017.002.000.000.000000, 2020/07/10
amdgpu 0000:03:00.0: vgaarb: deactivate vga console
...
amdgpu 0000:03:00.0: SMU: No response msg_reg: 6 resp_reg: 0
amdgpu 0000:03:00.0: Failed to enable requested dpm features!
amdgpu 0000:03:00.0: Failed to setup smc hw!
amdgpu 0000:03:00.0: hw_init of IP block <smu> failed -62
amdgpu 0000:03:00.0: amdgpu_device_ip_init failed
amdgpu 0000:03:00.0: Fatal error during GPU init
```

Omarchy's initramfs (`/etc/mkinitcpio.conf.d/omarchy_hooks.conf`) includes **both** `plymouth` and `kms`. On this hardware that means `amdgpu` modesets **before** the LUKS prompt. Combined with `quiet splash loglevel=0 vt.global_cursor_default=0`, there is no fallback console once the GPU dies.

### Workaround that actually reaches a desktop

Adding these to the live Limine `linux-t2` cmdline:

```
plymouth.enable=0 nomodeset
```

keeps the EFI simple-framebuffer. Hyprland then starts on `Unknown-1` at 3840×2160 (software rendering, no `amdgpu` bound). That is enough to use the machine, but it is not GPU support.

Those flags must be persisted with `KERNEL_CMDLINE[default]+=` in `/etc/default/limine` (or a drop-in under `/etc/limine-entry-tool.d/`) and rebuilt with `limine-mkinitcpio`. Editing `/boot/limine.conf` alone is lost on the next regenerate.

### What I'd like Omarchy to do for future installs

Not asking for a perfect Navi 14 Apple VBIOS driver. Asking that a 2020 T2 iMac **boots to a visible LUKS prompt and a desktop** without a manual bootloader edit.

Suggested installer/docs changes:

1. **Detect these machines** in `install/hardware/apple/` (DMI `iMac20,1` / `iMac20,2`, and/or Apple Navi 14 `1002:7340` with no Intel VGA device). `fix-t2.sh` currently prints "Detected MacBook with T2 chip" for every T2 PCI ID, including iMacs.
2. **Keep the EFI framebuffer alive through LUKS** on that hardware. Minimum that unblocked this box: persist `plymouth.enable=0 nomodeset` via `KERNEL_CMDLINE[default]+=` next to `t2-mac.conf`, then rebuild. Better if you can avoid shipping `nomodeset` forever: skip early `kms`/`plymouth` for this GPU, or try `amdgpu.dpm=0` (not tested here) so `amdgpu` can actually bind.
3. **Document iMac20,1 and iMac20,2** on the Mac support T2 list, with the AMD 5K-panel caveat. Same class of gap as the 2015 5K iMac write-up in https://github.com/omacom/omarchy/discussions/5151 (different GPU, same "stock Omarchy does not modeset this Apple AMD panel").

Related: t2linux treats AMD GPUs as only partly working; linux-t2 even carries `6001-drm-amd-pm-Fix-boot-problems-in-5300.patch` for this exact GPU family. The Omarchy T2 path still assumes the display will come up the MacBook way.