ACRN Project Technical Community Meeting Miutes - 9/19/2018
Minutes Achieve: https://docs.google.com/document/d/1VSAbg33qcF3Ee0kQ4MWjcN4YRwpGUWpakqA0IWVGtwQ/edit#
ACRN Project TCM - 19th September 2018
1.1 ACRN community survey: need to provide more technical docs, user case, invite joint design.
1.2 Open Source version Android (a.k.a “Celadon”) open sourced.
1.3 Slimboot Loader project open sourced. https://github.com/slimbootloader
Download foil from ACRN Presentation->ACRN_TCM->WW38’18.
Q: MISRA C will apply to ACRN, SOS, DM? A: As first step, only ACRN hypervisor itself will go through MISRA C compliance. It does not include the SOS yet. We may switch to VxWorks which is safety. In that case, we don’t to apply MISRA C to it. Otherwise, it requires more efforts. Then we can move to next level, like DM if it required.
Q: What is the safety integrity level ACRN targets at? Is absence of dynamic memory allocation highly recommended for such levels?
A: Static resource allocation is highly recommended for SIL 3/ASIL B and above, in addition to being a required directive in MISRA C. To make it possible for ACRN to be certified for a high safety integrity level, we consider static resource allocation mandatory, at least for releases to our customers who want to integrate ACRN in safety-critical use cases.
Q: There’re two option proposals for the implementation. Can an EPT find an address by VM id index and GPA? A: If we want to support free page table when runtime, another input parameter ‘page table level’ may needs. If not, VM id index is enough.
Q: What’s performance impact on using large EPT page tables ? A: 2~4% performance gain in server platform. For RT VM, maybe use small page table. That depends the special runtime situation on the special hardware platform.
Q: If the performance gain to use large EPT page tables is not critical, can we just simple the code not to merger the small dis-contiguous to a large EPT page table when runtime ? A: Let’s see. As the first step, we should remove the dynamic allocation to meet the FuSA’s requires. If it’s performance critical then we would do it later. It would much easier to merge it after we implement the static memory allocation since it’s a contiguous array.
Q: How to configure the system memory if using static memory allocation ? A: ACRN is for IoT embedded system. The SW should be shipped along with HW. The configuration is fixed. And it will not apply to platform with the different hardware. For developer, you should use Kconfig to configure it by yourself.
Q: Will ACRN keep the error code in static memory allocation case or keep dynamic allocation for open source release ? A: No, we could ASSERT the system since it would never fail. As for whether needs to keep the dynamic allocation for open source release, it’s an open to be closed.
Tel: +86-21-6116 7445
MP: +86-1364 1793 689