kernel: force amdgpu init on boot

modules/desktop-common.nix

@@ -193,6 +193,14 @@
           DRM_I915 = lib.mkForce no;
           DRM_XE = lib.mkForce no;
 
+          # early-boot framebuffer chain: drop every alternative to amdgpu so
+          # the console never transitions simpledrm -> dummy -> amdgpu (visible
+          # as a flash + scrolled dmesg). amdgpu owns the display from initrd
+          # onward; pre-amdgpu kernel output stays in the printk ring buffer.
+          DRM_SIMPLEDRM = lib.mkForce no;
+          FB_EFI = lib.mkForce no;
+          FB_VESA = lib.mkForce no;
+
           # intel cpu / platform
           INTEL_IOMMU = lib.mkForce no;
           INTEL_IDLE = lib.mkForce no;
@@ -325,12 +333,12 @@
     initrd = {
       systemd.enable = true;
       compressor = "zstd";
+      kernelModules = [ "amdgpu" ]; # own the display from initrd, no fbcon handoff
       availableKernelModules = [
         "xhci_pci"
         "thunderbolt"
         "nvme"
         "usbhid"
-        "amdgpu"
       ];
     };