Fixes the missing login screen (SDDM), akmod-nvidia compilation failures, and KDE Plasma Wayland desktop failing to load after login on Fedora Rawhide (Fedora 46+) and Linux kernel 7.4+ with NVIDIA GPUs (akmod-nvidia / nvidia-drm).

Symptoms

After upgrading to Linux 7.4.0-rc0+ kernels on Fedora Rawhide:

Missing Login Screen: Your monitor stays black or drops to a text console on tty1 instead of displaying the SDDM login screen.
Desktop Does Not Load After Login:
- Authenticating via PAM on tty1 starts startplasma-wayland, but the monitor remains blank.
- Switching to tty2–tty6 only opens a text shell.

akmods Build Fails on Upstream Changes:

Kernel 7.4.0-0.rc0.261026+:

akmods: Building and installing nvidia-kmod [FAILED]
nvidia-drm/nvidia-drm-drv.c:67:10: fatal error: drm/drm_fb_helper.h: No such file or directory
   67 | #include <drm/drm_fb_helper.h>
      |          ^~~~~~~~~~~~~~~~~~~~~

Kernel 7.4.0-0.rc0.261028+:

nvidia-uvm/uvm_hmm.c:4040:29: error: ‘VM_SPECIAL’ undeclared (first use in this function)
 4040 |            (vma->vm_flags & VM_SPECIAL) ||
      |                             ^~~~~~~~~~
nvidia-uvm/uvm_hmm.c:4042:12: error: implicit declaration of function ‘is_vm_hugetlb_page’
 4042 |            is_vm_hugetlb_page(vma);
      |            ^~~~~~~~~~~~~~~~~~

nvidia-fallback.service loads nouveau, causing kwin_wayland ERANGE:

systemd[1]: Starting nvidia-fallback.service - Fallback to nouveau as nvidia did not load...
sddm[...]: The configured theme "01-breeze-fedora" doesn't exist, using the embedded theme instead
sddm-helper-start-wayland[...]: "kwin_wayland_drm: Failed to create framebuffer: Numerical result out of range"
sddm-greeter-qt6[...]: There are no outputs - creating placeholder screen

Root Causes

flowchart TD
    A["Linux 7.4-rc0 Kernel Updates"] --> B["Header Move: drm_fb_helper.h -> clients/drm_fbdev_helper.h"]
    A --> C["MM API Cleanup: VM_SPECIAL & is_vm_hugetlb_page removed"]
    B --> D["nvidia-drm-drv.c fails compilation"]
    C --> E["nvidia-uvm/uvm_hmm.c fails compilation"]
    D --> F["akmods fails to build kmod-nvidia"]
    E --> F
    F --> G["nvidia-fallback.service loads nouveau"]
    G --> H["kwin_wayland fails DRM framebuffer (ERANGE: Numerical result out of range)"]
    H --> I["KWin creates headless placeholder screen (0 physical outputs)"]
    I --> J["SDDM Greeter & KDE Plasma Wayland render to invisible placeholder (Blank Screen)"]

Kernel DRM Header Move (<drm/drm_fb_helper.h> → <drm/clients/drm_fbdev_helper.h>): Upstream moved include/drm/drm_fb_helper.h to include/drm/clients/drm_fbdev_helper.h. Both nvidia-drm/nvidia-drm-drv.c and conftest.sh in nvidia-kmod (<= 615.78.08) unconditionally include <drm/drm_fb_helper.h>, breaking build.
Kernel MM API Removals (VM_SPECIAL and is_vm_hugetlb_page): In 7.4.0-0.rc0.261028+:
- VM_SPECIAL was removed from <linux/mm.h>.
- is_vm_hugetlb_page() was removed from <linux/hugetlb.h> / <linux/hugetlb_inline.h> in favor of vma_is_hugetlb(). nvidia-uvm/uvm_hmm.c fails compilation when calling these macros.
nouveau Fallback + NVIDIA Userspace Libraries Break kwin_wayland_drm: When nvidia.ko fails to load, nvidia-fallback.service loads nouveau. With xorg-x11-drv-nvidia-libs installed, kwin_wayland fails DRM framebuffer creation with Numerical result out of range (ERANGE) and falls back to a virtual headless placeholder screen (There are no outputs - creating placeholder screen), leaving both SDDM and the user's Plasma Wayland desktop invisible.
Missing 01-breeze-fedora SDDM Theme: During Fedora KDE Plasma upgrades, sddm-breeze may be absent while display-manager.service still points to sddm.service.

Quick Start (One-Command Fix)

Clone the repository from a TTY (Ctrl+Alt+F3) or SSH session and run the repair script:

git clone https://github.com/Heretek-AI/fedora-nvidia-kernel-7.4-fix.git
cd fedora-nvidia-kernel-7.4-fix
sudo ./fix-nvidia-sddm.sh

Or run directly with curl:

curl -fsSL https://raw.githubusercontent.com/Heretek-AI/fedora-nvidia-kernel-7.4-fix/main/fix-nvidia-sddm.sh | sudo bash

Read-Only Diagnosis

To inspect your system without making any changes:

./fix-nvidia-sddm.sh --diagnose

What `fix-nvidia-sddm.sh` Does

Restores <drm/drm_fb_helper.h> Compatibility: Creates relative symlinks include/drm/drm_fb_helper.h -> clients/drm_fbdev_helper.h across all installed Linux 7.4+ /usr/src/kernels/* trees.
Installs Persistent Kernel Hooks:
- Installs /etc/kernel/install.d/90-nvidia-drm-fb-helper-compat.install so Fedora's kernel-install runs the link before 95-akmodsposttrans.install.
- Installs /etc/kernel/postinst.d/99-nvidia-drm-fb-helper-compat for fallback package managers.
Patches akmods Source Package: Updates /usr/src/akmods/nvidia-kmod.latest with both the DRM fbdev helper and UVM VM_SPECIAL/hugetlb compatibility patches, allowing akmods to compile cleanly for any future kernel build.
Rebuilds & Installs kmod-nvidia: Runs akmods --force --kernels <kver> and depmod -a (or installs matching prebuilt RPMs).
Restores sddm-breeze: Ensures the 01-breeze-fedora SDDM theme is installed when sddm.service is active.
Activates nvidia_drm: Attempts to unload nouveau and start nvidia_drm (modeset=1) + sddm.service live, or prompts for sudo systemctl reboot if nouveau is bound to the kernel framebuffer (fb0).

Repository Contents

Path	Description
`fix-nvidia-sddm.sh`	Diagnostic (`--diagnose`) and automated repair script for Fedora / Linux 7.4+
`hooks/90-nvidia-drm-fb-helper-compat.install`	`/etc/kernel/install.d/` hook for Fedora `kernel-install`
`hooks/99-nvidia-drm-fb-helper-compat`	`/etc/kernel/postinst.d/` hook fallback
`patches/nvidia-drm-linux-7.4-fbdev-helper.patch`	Clean patch for `nvidia-drm-drv.c` and `conftest.sh` using `__has_include(<drm/clients/drm_fbdev_helper.h>)`
`patches/nvidia-uvm-linux-7.4-vm-special-hugetlb.patch`	Compatibility patch for `nvidia-uvm/uvm_hmm.c` restoring `VM_SPECIAL` and `is_vm_hugetlb_page` shims
`LICENSE`	MIT License

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fedora-nvidia-kernel-7.4-fix