https://bugs.freedesktop.org/show_bug.cgi?id=105996
--- Comment #5 from Shawn Starr shawn.starr@rogers.com --- For reference compiling amdgpu.ko with custom patch on a Fedora kernel:
1) rpm -ivh kernel-4.17.0-0.rc0.git7.2.fc29.src.rpm
2) Copy custom patch into rpmbuild/SOURCES
3) Modify kernel.spec to add patch into the listing
4) cd ~/rpmbuild/SPECS; rpmbuild -bp kernel.spec
5) cd ~/rpmbuild/BUILD/kernel-4.16.fc27/linux-4.17.0-0.rc0.git7.2.fc29.x86_64
6) vi Makefile --> add the proper matching kernel version '-0.rc0.git7.2.fc29.x86_64' to EXTRAVERSION.
7) cp /boot/config-4.17.0-0.rc0.git7.2.fc29.x86_64 ~/rpmbuild/BUILD/kernel/4.16.fc17/linux-4.17.0-0.rc0.git7.2.fc29.x86_64/.config
8) cp /lib/modules/4.17.0-0.rc0.git7.2.fc29.x86_64/build/Module.symvers ~/rpmbuild/BUILD/kernel/4.16.fc17/linux-4.17.0-0.rc0.git7.2.fc29.x86_64/
9) cd ~/rpmbuild/BUILD/kernel/4.16.fc17/linux-4.17.0-0.rc0.git7.2.fc29.x86_64/certs && cp ~/rpmbuild/SOURCES/x509.genkey .
10) cd .. && make certs
11) make modules_prepare
12) make M= drivers/gpu/drm/amd/amdgpu modules
13) ./scripts/sign-file sha256 certs/signing_key.pem certs/signing_key.x509 drivers/gpu/drm/amd/amdgpu/amdgpu.ko
14) compress kernel modules with xz
15) Replace/move original in /lib/modules/4.17.0-0.rc0.git7.2.fc29.x86_64/drives/dpu/drm/amd/amdgpu/ of way
16) depmod -a
17) Remove old initramfs and rebuild with dracut