New Linux Tool Brings Resizable BAR to Intel Arc GPUs on Old Motherboards

“The fix targets the PCIe switch built into Arc cards, whose small upstream BAR blocks Linux from enlarging the GPU's memory window. arc-rebar writes the card's ReBAR register, then removes and rescans the root port. Intel engineers have proposed a kernel-level fix for this, though it hasn't been merged yet. On a Supermicro X9DRH-7TF with dual Xeon E5-2670 v2 CPUs and a 2015 BIOS, a B580 went from 256 MiB of CPU-visible VRAM to a 16 GiB window covering all 12 GB. Measured VRAM bandwidth jumped from 15 GB/s to 392 GB/s, and a 4K Vulkan blur that used to stall ran at 39 to 50 FPS.


Above 4G Decoding is still needed, and the GPU must sit on its own root port. Only Battlemage has been tested, though the developer expects Alchemist to behave the same way. The tool is built for Debian and Ubuntu, so Windows gamers won't benefit, but it could make Arc a viable option for older servers and workstations.“

Source: https://www.techpowerup.com/354116/...ble-bar-to-intel-arc-gpus-on-old-motherboards