Page History

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Minute takers according to this page 

April 30, 2019

Participants

• Gunnar

Apologies

Minutes

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April 23, 2019

Participants

• Gunnar
• Artem
• Dmitry
• Matti
• Philippe
• Franz
• Bernhard

...

• Matt Spencer (ARM)

Minutes

USB Virtualization

• Android Debug (ADB): Google demands access to this interface for production programmsprograms
  • We have previously seen almost exclusively Host role requirements in Automotive, i.e. the car/ECU has the USB Host Role and furthermore assumed that there is little need for USB On-the-go (OTG)
  • ... but this suggests the device role will be required (through the Google requirements), and also that OTG becomes a bit more likely to be included (to "solve" the need for both Host and Device roles)
  • If hardware allows, this could of course be a single device port, and passed through to Android OS

• New Input documents
  • Hardware manual for Intel which includes description of hardware assisted virtualization.
  • ACRN implementation for USB
• USB device virtualization discussion: (i.e. the ECU implements device role)
  
  • In general a USB device is considered as 1 hardware unit, thus we need to document how a pass through implementation can be implemented
  • (NOTE: In this discussion we were jumping a bit back and forth between Host and Device virtual discussion)
  • We can (for both Host and Device) look at the ACRN implementation, Gunnar showed a picture which Artem has sent to him
    • Its
  USB device virtualization discussion:
  
  • In general a USB device is considered as 1 hardware unit, thus we need to document how a pass through implementation can be implemented
    • We can refer to the ACRN implementation, Gunnar showed a picture which Artem has sent to him USB architecture shows that you have a Service OS which talks to the phy mux control and the xHCI controller
    • the The USER Operating Systems have only access to the xDevice Controller Interface (DCI)
    • OTG needs to be covered as well
    • ReDiscussion:  Re-use of interfaces from the Intel ACRN hypervisor should can be considered for the GENIVI specificationa standards attempt?
      
      • TBD: if this interface does cover other architectures e.g. Arm ARM as well?
        • Rensas and Qualcomm have differenent implementations
      Use-cases which needs
• Host role virtualization...
• Need a way to assign policies for sharing
• Discussing EHCI, XHCI, ....  Is assuming XHCI transport a way forward?
• Matti: But we need some kind of hardware neutral abstraction
• Artem: Agreed, but XHCI seems to be a kind of superset - could it be the HW independent (superset) interface?
• Artem: VMM enumerates device in DOM0
• Gunnar: This is what I mean by Hypervisor must implement some part of stack, handle attach and initial reading of device IDs for example, if they are to be filtered and passed to only one OS.  But what we mean by "in the Hypervisor" might differ in different HV architectures.
• Use-cases which need to be considered for USB host mode virtualization: USB tethering (e.g. , and phone "projection" / Apple Car Play), USB Switch support, mass-storage-device,Traffic Signal & Toll-booth beacon external device.  
• Limitations, often only one USB controller, therefore switch.
• How supporthow does synchronizations between the host/service OS (dom0Xen: Dom0) and User OSS OSes (VMs) work?
• We need more use cases...
• Gunnar: Yes but maybe enough to agree the need is there (for Host virt).   E.g. those device types that were mentioned already.  E.g.: Mass storage to one OS, toll-booth device to another.
• ...
• Device controller
• Matti: How does XHCI map to MMIO based controllers?
• ... Right we must consider how IOMMU virtualisation affects this
• Artem: Yes it depends if PCIe is used or not (XHCI usually on PCIe)
•  USB over IP implementation in Linux - is this an appropriate/reusable protocol?

AMM

• Arm SCMI presentation Geniviat GENIVI AMM (HV workshop), Arm experts will be there. Gunnar to check if there is an space for a speaking slot

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