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LCA14: LCA14-101: ARM VM Standards


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Resource: LCA14
Name: LCA14-101: ARM VM Standards
Date: 03-03-2014
Speaker: Christoffer Dall

Published in: Technology
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LCA14: LCA14-101: ARM VM Standards

  1. 1. Mon-3-Mar, 10:05am, Christoffer Dall LCA14-101: ARM VM Standards
  2. 2. • Discussion at LCU13 • Trying to answer main question: How do distribution vendors package and ship ARM VMs so that they can be expected to run on the ARM hypervisors out there? Background
  3. 3. • RFC sent to: • • • • • Proposed ARM VM Image Spec
  4. 4. • Build single image, run everywhere • Valid recommendations for both aarch32 and aarch64 • The SBSA doesn’t cover it • Mandated EL2 • Mandates pl011 • aarch32 not supported Goal
  5. 5. • Must be well-defined • Must be GPT with EFI application in EFI System Partition (ESP) • Must use removable path (no preexisting UEFI config) • Supports both KVM and Xen • Example: Grub2 as EFI application loads Linux Image Format
  6. 6. • Required: Must be able to boot EFI application in ESP • Obvious recommendation is UEFI implementation • Linaro is already working on this • Recommended to support persistent environment storage: • Supports adding disks later • Supports running installers later • Firmware distributed as part of distribution, not with VM image Virtual Firmware
  7. 7. • The Linux kernel boot protocol requires an FDT • Even when using ACPI and UEFI • FDT -> UEFI System Table -> ACPI root pointer • Therefore: • ACPI is discoverable through FDT, or • the FDT describes the system directly Hardware Description
  8. 8. • Must support at least one of: • (1) aarch32 on aarch32 • (2) aarch32 on aarch64 • (3) aarch64 on aarch64 • Mandatory peripherals: • Serial console (pl011, virtio-console, or Xen PV console) • GICv2 or newer • Architected Timer • Hotpluggable bus (virtual PCIe or Xen PV bus) VM Platform
  9. 9. • Must support GICv2 and newer. Maintaining backwards compatibility. • Strongly recommended to support all of: • block, network, console, balloon drivers, e.g. • virtio-pci • virtio-mmio • Xen PV drivers • Will leverage mach-virt kernel facilities, but these are loosely coupled concepts. Guest OS Recommendations
  10. 10. • Mandate serial port (reduced pl011) • Use cases for ACPI (device assignment, verification, unification) • Fixed memory map (UEFI) • Issue concerning kernel comand line (console=?) Open Questions
  11. 11. • RFC: • Questions? Resources and Questions
  12. 12. More about Linaro Connect: More about Linaro: More about Linaro engineering: Linaro members: