Intel will provide Resizable BAR Support for its Arc Alchemist GPUs on Linux Platforms

Resizable BAR was all the rage in 2020, with both AMD and NVIDIA activating support for the feature on their graphics cards. Now, Intel has announced that the technology will…

By Nivedita Bangari

January 31, 2022

2 min read

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Resizable BAR was all the rage in 2020, with both AMD and NVIDIA activating support for the feature on their graphics cards. Now, Intel has announced that the technology will be supported on their future Arc Alchemist GPUs.

According to a report by Phoronix, the newest Linux graphics kernel has fixes for ‘Resizable BAR’ or ReBAR functionality. On the Linux platform, the current patches offer a tiny BAR recovery support for Intel’s Kernel graphics driver. The following is a quote from the patch:

Starting from DG2 we will have resizable BAR support for device local-memory, but in some cases, the final BAR size might still be smaller than the total local-memory size. In such cases, only part of the local memory will be CPU accessible, while the remainder is only accessible via the GPU. This series adds the basic enablers needed to ensure that the entire local-memory range is usable.

via Phoronix

Given that the patch was pushed out for Linux 5.17, the Resizable BAR support is likely to be enabled as early as Linux 5.18. Users who want to use ReBAR with Intel’s GPUs in the Linux ecosystem must upgrade to the most recent Linux and MESA builds. Intel already has Resizable BAR support on its desktop platforms, beginning with the 300-series, and given that other GPU manufacturers are delivering the technology on both desktops and laptops, it’s probable that Intel will do the same with its Arc Alchemist GPU lineup.

Today’s PCs are often limited to 256 MB of mapped memory, and ReBAR effectively limits how much discrete GPU memory space can be mapped. BAR allows the system to access full GPU RAM, reducing bottlenecks and allowing for quicker performance. BAR’s performance results have been inconsistent so far, with boosts in some titles and no performance benefits in others. There are a few circumstances when the system performs worse with BAR enabled, but this is a small percentage of the time, so having it enabled isn’t a bad idea, and it’s nice to see Intel attempting to make such things open-source.