Rod Burlamaqui releases arc-ReBAR Linux tool for Intel Arc ReBAR support

Developer Rod Burlamaqui has released arc-rebar, a Linux tool designed to enable Resizable BAR for Intel Arc GPUs on motherboards that do not offer a ReBAR option. It executes during every startup from the initramfs prior to loading the graphics driver. It does not modify the kernel, Intel drivers, or the BIOS.

The utility functions by adjusting the ReBAR register for the PCIe switch inside Arc cards before removing and rescanning the root port. On a Supermicro X9DRH-7TF with a 2015 BIOS, testing showed a B580 expanded its CPU-accessible memory space from 256 MiB to a 16 GiB window. In that setup, VRAM bandwidth increased from 15 GB/s to 392 GB/s, and a 4K Vulkan blur test ran at 39 to 50 FPS instead of stalling.

Users still need Above 4G Decoding enabled, and the GPU must sit on its own root port. The software supports Ubuntu and Debian, meaning Windows users cannot use it. While only Battlemage has been tested, Burlamaqui expects Alchemist cards to behave the same way. Staff at Intel have suggested an official kernel patch to address this, though it has not been merged yet.