Bug#969755: nvidia-legacy-390xx-kernel-source: fails to build with module-assistant and NV_EXCLUDE_KERNEL_MODULES=nvidia-uvm

[Kevin Locke]

Package: nvidia-legacy-390xx-kernel-source
Version: 390.138-2
Severity: normal

Dear Maintainer,

I attempted to build nvidia-legacy-390xx-kernel-source against kernel
5.8.7 using module-assistant with NV_EXCLUDE_KERNEL_MODULES=nvidia-uvm
set in the environment, as suggested for dkms in the changelog.  It
failed with the following error:

$ NV_EXCLUDE_KERNEL_MODULES=nvidia-uvm m-a a-i -t -l 5.8.7 nvidia-legacy-390xx-kernel-source
[... omit many lines of output ...]
make[1]: Leaving directory '/usr/src/modass/usr_src/modules/nvidia-legacy-390xx-kernel'
mv nvidia.ko nvidia-legacy-390xx.ko
mv nvidia-modeset.ko nvidia-legacy-390xx-modeset.ko
mv nvidia-drm.ko nvidia-legacy-390xx-drm.ko
mv nvidia-uvm.ko nvidia-legacy-390xx-uvm.ko
mv: cannot stat 'nvidia-uvm.ko': No such file or directory
make: *** [debian/rules:51: build-stamp] Error 1
BUILD FAILED!

It appears that nvidia-uvm.ko was not built (as intended) but
debian/rules fails when it does not exist.  Is there a way to build
against 5.8 with module-assistant, or is dkms required?

Thanks,
Kevin