This paper introduces standardized gem5 resources (disk images, kernels and workloads) and new features (hypercalls, Suite, MultiSim) to enhance reproducibility in gem5-based research. All the contributions of this paper are upstreamed to the main gem5 repository and are available in release v25.0 and later. The source for building all the resources mentioned in this paper is available in the gem5 resources repository. For ease of access, we have also created a Zenodo archive with all the sources and scripts needed to run a representative simulation in gem5. Since the paper includes a building multiple disk images and workloads across different ISAs that in total will take weeks to run, the instructions here will focus on re-building the NPB disk image from the provided base image and running the NPB BT Size S workload as an example.