Looking at 4.19.26 it seems the PCI ID for the 9900k is missing and was later added to 4.20 in the following patch. https://patchwork.kernel.org/patch/10555527/
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/include/drm/i915_pciids.h?h=v4.19.26#n388
I'll have a go at applying the patch one evening this week
root:/$ uname -s -r -v -p && lspci | grep 3e98; ls /dev/dri; modprobe i915; ls /dev/dri
Linux 4.19.24-Unraid #1 SMP Thu Feb 21 11:37:54 PST 2019 Intel(R) Core(TM) i9-9900K CPU @ 3.60GHz
00:02.0 VGA compatible controller: Intel Corporation Device 3e98
/bin/ls: cannot access '/dev/dri': No such file or directory
/bin/ls: cannot access '/dev/dri': No such file or directory
root:/$ dmesg | grep -A 4 -B 8 vga
[ 2.507344] ACPI: PCI Interrupt Link [LNKA] (IRQs) *0
[ 2.507360] ACPI: PCI Interrupt Link [LNKB] (IRQs) *1
[ 2.507375] ACPI: PCI Interrupt Link [LNKC] (IRQs) *0
[ 2.507391] ACPI: PCI Interrupt Link [LNKD] (IRQs) *0
[ 2.507406] ACPI: PCI Interrupt Link [LNKE] (IRQs) *0
[ 2.507421] ACPI: PCI Interrupt Link [LNKF] (IRQs) *0
[ 2.507436] ACPI: PCI Interrupt Link [LNKG] (IRQs) *0
[ 2.507451] ACPI: PCI Interrupt Link [LNKH] (IRQs) *0
[ 2.507758] pci 0000:00:02.0: vgaarb: setting as boot VGA device
[ 2.507758] pci 0000:00:02.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
[ 2.507758] pci 0000:00:02.0: vgaarb: bridge control possible
[ 2.507758] vgaarb: loaded
[ 2.507758] SCSI subsystem initialized
[ 2.507758] libata version 3.00 loaded.
[ 2.507758] ACPI: bus type USB registered
[ 2.507758] usbcore: registered new interface driver usbfs
Apologies i was looking at the tags in the drm repo on freedesktop, and assumed they were also releasing them independently turns out that's for the user space component.