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Bug 1844279

Summary: [Docs] [vGPU] Document the 'nodisplay' option when adding mdev custom property
Product: Red Hat Enterprise Virtualization Manager Reporter: Germano Veit Michel <gveitmic>
Component: DocumentationAssignee: Donna DaCosta <ddacosta>
Status: CLOSED CURRENTRELEASE QA Contact: rhev-docs <rhev-docs>
Severity: medium Docs Contact:
Priority: unspecified    
Version: 4.3.9CC: ctomasko, lsurette, mavital, mhicks, mkalinin, srevivo
Target Milestone: ovirt-4.4.5Keywords: Documentation, NoDocsQEReview
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Hardware: x86_64   
OS: Linux   
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Last Closed: 2021-04-13 14:38:56 UTC Type: Bug
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oVirt Team: Docs RHEL 7.3 requirements from Atomic Host:
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Description Germano Veit Michel 2020-06-05 00:07:44 UTC 
Description of problem:

In RHV 4.3.5+ there was a change of logic on how vGPU works via BZ1723580 and the Documentation does not seem to have been updated. The custom property 'nodisplay' is not explained in the relevant documentation [1].

4.3.4 and lower:  VM runs with both vGPU and a QXL/VGA device, while Spice/VNC console uses the QXL/VGA device and is always available
4.3.5 and higher: VM runs only with vGPU, Spice/VNC console is a blank screen until the VM initializes the display when Xorg/GDM loads.

However, at the same time the change was introduced, an option was also made available to override this new behaviour. The option is "nodisplay" and is to be added together with the nvidia-XXX custom property in Step 2.1.11 in [1].

For example:
"nodisplay,nvidia-12"

This option should make the vGPU hostdev not be set with "display=on" and also add back the QXL/VGA video device.

[1] https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.3/html/setting_up_an_nvidia_gpu_for_a_virtual_machine_in_red_hat_virtualization/assigning_virtual_gpus#proc_setting-up-nvidia-vgpu-devices_nvidia_vgpu