A developer has enabled Resizable BAR for Intel Arc graphics cards on older Linux systems without requiring BIOS modifications, custom drivers or kernel patches.
According to VideoCardz the utility, called arc-rebar, could make Chipzilla’s graphics cards more useful in machines whose motherboard manufacturers stopped issuing meaningful updates years ago.
Intel recommends Resizable BAR for optimal Arc performance. The feature lets the processor access more graphics memory, avoiding the limits of a small memory window.
The developer tested the workaround on a Supermicro X9DRH-7TF motherboard with an Intel C602 chipset, dual Xeon E5-2670 v2 processors, and 2015 BIOS firmware.
An Arc B580 with 12GB of graphics memory handled the GPU duties, while Debian 13 supplied the operating system.
Before applying the workaround, the card exposed just 256MiB of CPU-accessible video memory. Afterwards, Linux allocated a 16GiB BAR window, allowing access to the card’s full 12GB.
That gives a decade-old platform another potential upgrade option, which is inconvenient for anyone hoping to sell its owner an entirely new computer.
In the developer’s sample workload, measured GPU memory bandwidth increased from 15GB/s to 392GB/s. A 4K Vulkan blur filter that previously stalled reached 39-50 frames per second.
Those results describe specific tests. Gaming performance depends on the application and the rest of the system, so buyers should keep expectations grounded and avoid the usual benchmark-induced hysteria.
The obstacle involves the integrated PCIe switch on Arc cards. An 8MB BAR on its upstream port can prevent Linux from expanding the GPU’s memory window.
The utility changes the BAR size and forces the PCIe root port to be re-enumerated during boot, allowing Linux to allocate the larger window.
Some hardware requirements remain. The motherboard must support Above 4G Decoding and provide sufficient memory-mapped I/O space above 4GB.
The graphics card needs a dedicated PCIe root port without other devices sharing it, restricting which configurations can use the workaround.
The utility currently supports Debian and Ubuntu installations, and recommends Linux kernel 6.12 or newer. Operation has been confirmed with Battlemage, while first-generation Alchemist cards remain untested.
