Hi Laura,
I tried cross-building it in the latest mock (1.4.11-1), with mock -r fedora-29-i386 --forcearch=i386 kernel-4.18.0-0.rc0.git9.1.fc29.src.rpm and it failed right after installing repos and keys: […] Finish: dnf install ERROR: Exception(kernel-4.18.0-0.rc0.git9.1.fc29.src.rpm) Config(fedora-rawhide-i386) 1 minutes 16 seconds INFO: Results and/or logs in: /var/lib/mock/fedora-rawhide-i386/result ERROR: Could not find useradd in chroot, maybe the install failed?
The logs don't mention something useful, and I won't be able to test on actual 32-bit hardware until later tonight.