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ReBarUEFI: Resizable BAR for almost any UEFI system

243 points · 77 comments · nateb2022

  1. bigwheels · · focus · HN ↗
    What does this do? I perused the README but I'm still clueless on what the purpose and use-case is for ReBAR.

    (Posting this under the assumption others will also appreciate a bit of quick context.)

    1. mathisfun123 · · focus · HN ↗
      > what the purpose and use-case is for ReBAR

      Literally the second sentence in the repo:

      > This provides performance benefits and is even required for Intel Arc GPUs to function optimally.

      1. qudat · · focus · HN ↗
        Your quote doesn’t help me understand this project at all.

        What is a BAR let alone a resizable one? Readme just jumps in, which is fine, but I’m not sure why this is on HN or why I should care.

        1. pizza234 · · focus · HN ↗
          ReBAR stands for "Resizable BAR (Base Address Register)" - it makes the CPU's access window into GPU memory resizable; instead of accessing VRAM in small chunks, the CPU can access much more at once, which can improve performance on some modern GPUs.
          1. docenttx · · focus · HN ↗
            Its also neccessary in many cases using any PCIe device with BAR-addressable memory on-board above the threshold, not just vram.
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