ACRN Project Technical Community Meeting Minutes - 10/31/2018

Wang, Hongbo

If Dial in: +1 877 369 0926 (Toll Free)
  1. ACRN project update
  1. ACRN talk in ELC meeting last week, there’s update about RT support, etc.
  2. TCM meeting new time from next week:
11AM (China), 9PM (Santa Clara), 6AM (London)
  1. Wu, Binbin:  ACRN VT-d
Download foil from ACRN Presentation->ACRN_TCM->WW44’18.
Q: What’s the difference b/w DMA address and HPA address?   A: In Guest, guest driver use GPA as DMA target address. DMA Remapping unit will translate the GPA to HPA, so that the device can access the memory directly.
Q: Why x86 devices can't access any memory address rather than only DMA addresses?  A: Not sure if understand the question correctly. DMA is the feature of computer systems that allows devices to access main system memory independent of the CPU.
Q: Will all the devices under one host bridge will be collectively assigned to a single VM?  A:  No. The case when a group of devices needs to be collectively assigned to a single domain, is that when these devices may have the same source-id (BDF) in the DMA requests.
If they share the same source id, DMA remapping hardware can’t uniquely identify the source of the requests. So they need to be assigned collectively.
Q:  What is iommu group? devices of same group can only be passthrough to one domain.  A: The same answer as the previous question.
Q: what should I do when I want pass though an device using DMA to VM. need modify bios? guest OS driver?
A: First, need to make sure that VT-d feature has been enabled in BIOS.
No need to modify guest OS driver. On ACRN, you can follow the steps to pass-through a PCI device (USB host controller) to a VM.
Q: When Guest OS issues an DMA request, How ACRN processes it, what is the detail sequence?
A: The DMA requests are initiated in guest OS by device driver.
If the device has been passed-through to a VM. The DMA operations can be completed without the intervention of hypervisor.
The DMA Remapping Unit will do the DMA address translation from GPA to HPA automatically.
Hypervisor is invoked only when guest software accesses protected resources that will impact system functionality and isolation (such as PCI configuration space accesses, interrupt management, etc.).
Q: IS VT-d enabled for graphics in ACRN?
A: When GVT-g (, which enables graphics sharing b/t multiple VM) is used as the graphics solution, the IOMMU for graphics device is not enabled in ACRN.
By default, GVT-g is enabled, so by default, IOMMU for graphics device is not enabled by default.
3. All: Community open discussion.
4. Next meeting agenda proposal:
WW Topic Presenter Status
WW21 ACRN roadmap introduction Ren, Jack Done
WW22 Patch submission process
ACRN feature list introduction
Wang, Hongbo
Ren, Jack
WW23 Memory Management Chen, Jascon Done
WW24 Boot flow and fast boot Wu, Binbin Done
WW25 Memory Management Chen, Jason C Done
WW26 Audio virtualization Li, Jocelyn Done
WW27 Trusty Security on ACRN Zhu, Bing’s team Done
WW28 Clear Linux and use on ACRN Du, Alek Done
WW29 GVT-g for ACRN (a.k.a AcrnGT) Gong, Zhipeng Done
WW30 Device pass-through Zhai, Edwin Done
WW31 ACRN logical partition Ren, Jack/Xu, Anthony Done
WW32 ACRN interrupt management Chen, Jason Done
WW33 ACRN ACPI virtualization Edwin Zhai Done
WW34 ACRN S3/S5 management Fengwei Yin Done
WW35 ACRN P-state/C-state management Victor Sun Done
WW36 CPU Virtualization Jason Chen Done
WW37 Joint Design: VM Configuration Options Discussion Fengwei Yin Done
WW38 Joint Design: Remove dynamic memory allocation from ACRN memory management Li, Fei Done
WW39 USB virtualization Wang, Yu Done
WW41 Interrupt Storm Mitigation Cao, Minggui Done
WW42 SBL bootloader introduction - 101 Ma, Maurice Done
WW43 SBL bootloader - 201 Ma, Maurice Done
WW44 ACRN VT-d Binbin Wu 10/31
In HV PCIe configuration space trap and emulation Chen, Zide Plan
vHost support Wang, Yu Plan
Virtio network performance analysis Deng, Jie Plan
Virtio storage performance analysis Chen, Conghui Plan
ACRN GPIO virtualization Wang, Yu Plan
DMA storm prevention Cao, Minggui Plan
IPU Sharing (TBD) Bandi, Kushal
CPU Sharing (TBD)
ACRN real-time (TBD)
vSBL Introduction (TBD)
Open Source Android (TBD)
  1. 2018 ELC solution world Congress
  1. Oct’18
  2. One talk and one demo accepted
  1. 2019 Embedded World Exhibition & Conference
  1. Feb. 26-28, 2019
  2. CFP deadline: Aug. 31, 2018
  3. Nuremberg, Germany
  1. Project URL:
  1. Portal:   
  2. Source code:   
  3. email: info@...g
  4. Technical Mailing list: acrn-dev@...g
  1. Recommended Hardware platform (reference):
  1. Apollo Lake (SoC) UP2 (with serial port): AAEON UPS-APLC2-A10-0232
  2. Apollo Lake (SoC) NUC (without serial port):
Kabylake (Core) NUC (with serial port): NUC7i5BNH
Best regards.
Tel: +86-21-6116 7445
MP: +86-1364 1793 689