tl;dr: ReBarUEFI is a UEFI DXE driver that enables Resizable BAR on systems lacking official support, by hooking into PciHostBridgeResourceAllocationProtocol during PCI enumeration to resize BARs based on an NVRAM variable. It includes UEFIPatch modifications to fix common firmware issues like 64-bit BAR handling and MMIO space limits across Sandy Bridge through Coffee Lake platforms. Useful for older systems running Intel Arc GPUs (which require ReBAR) or gaining measurable performance in games—the author reports up to 12% FPS gains on an i5-3470 with an RX 580.