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  1. Red Hat OpenStack Services on OpenShift
  2. OSPRH-76

Add "bochs" as a possible video display device option

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    • Icon: Epic Epic
    • Resolution: Done-Errata
    • Icon: Minor Minor
    • rhos-18.0.0
    • rhos-18.0.0
    • openstack-nova
    • None
    • Add "bochs" as a possible video display device option
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    • False
    • Committed
    • Committed
    • OSP-14492 - Enable agnostic new device hardware with multi-vendor migration capabilities
    • openstack-nova-27.1.1-18.0.20230930093334.a869ab1.el9ost
    • Committed
    • Committed
    • 33% To Do, 0% In Progress, 67% Done
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      .Support for the `bochs` libvirt video model

      This release adds the ability to use the `bochs` libvirt video model. The `bochs` libvirt video model is a legacy-free video model that is best suited for UEFI guests. In some cases, it can be usable for BIOS guests, such as when the guest does not depend on direct VGA hardware access.
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      .Support for the `bochs` libvirt video model This release adds the ability to use the `bochs` libvirt video model. The `bochs` libvirt video model is a legacy-free video model that is best suited for UEFI guests. In some cases, it can be usable for BIOS guests, such as when the guest does not depend on direct VGA hardware access.
    • Enhancement
    • Done
    • Automated

      What?


      Add the "bochs" display device as one of the possible video models.

      This will be an addition to the several possible models that Nova
      already supports today: (CIRRUS, QXL, VGA, VMVGA, XEN, VIRTIO, GOP,
      NONE)

      Why?


      The 'bochs' display device is a recommended[1] safe option for UEFI
      guests. This is supported in libvirt from version 5.6.0; Nova upstream's
      current MIN_LIBVIRT_VERSION (6.0.0) satisfies this requirement.

      More details
      ------------

      Partially quoting the "bochs display device" section from a post written
      by a QEMU graphics maintainer[1]:

      [quote]
      [...] Main advantage over standard VGA is that this device is alot
      simpler. The code size and complexity needed to emulate this device
      is an order of magnitude smaller, resulting in a reduced attack
      surface. Another nice feature is that you can place this device in a
      PCI Express slot.

      For UEFI guests it is safe to use the bochs display device instead
      of the standard VGA device. The firmware will setup a linear
      framebuffer as GOP anyway and never use any legacy VGA features.

      For BIOS guests this device might be useable as well, depending on
      whenever they depend on direct VGA hardware access or not. There is
      a vgabios which supports text rendering on a linear framebuffer, so
      software which uses the vgabios services for text output will
      continue to work. Linux bootloaders typically fall into this
      category. The linux text mode console (vgacon) uses direct hardware
      access and does not work. The framebuffer console (fbcon running on
      vesafb or bochs-drm) works.
      [/quote]

      [1] https://www.kraxel.org/blog/2019/09/display-devices-in-qemu/

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              Created:
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