If you need to test a custom version of grub2 you can follow the steps bellow to build the necessary packages for RHEL8 (it should also work on CentOS and Fedora):
subscription-manager register --username USER --password PWD --auto-attach subscription-manager repos --enable codeready-builder-for-rhel-8-ppc64le-rpms dnf update dnf install dnf-utils dnf groupinstall 'Development Tools' yumdownloader --source grub2 rpm -ivh ./grub2-2.02-90.el8.src.rpm dnf builddep ~/rpmbuild/SPECS/grub2.spec scp -rp ./YOUR_FIX_OR_FEATURE.patch ~/rpmbuild/SOURCES/ vi ~/rpmbuild/SOURCES/grub.patches and add a new item at the end of the file: Patch0318: YOUR_FIX_OR_FEATURE.patch cd ./rpmbuild/ rpmbuild -bb ./SPECS/grub2.spec cd ./RPMS/ cd ./ppc64le/ rpm -ivh --force ./*