On QEmu PCI Express (pcie)

No one objected pcie support itself. But patch quality is another issue. Someone commented that the merge might be slow because pcie support is not urgent.



Some people are interested in multi pci buses instead of pcie itself because just 32 (- some) slots is too few. The irusage model is a VM as file server with high end storage. They want many LUs to be attached to host and export them to guest VM.

9th Aug.

LinuxCon Mini Summit: KVM-forum


  • Desktop Virtualization with SPICE

    • Gerd Hoffman
    • He talked about SPICE. The main part is QXL,virtual display device, and its device driver.
    • It supports multi display and he demoed it.
    • Interesting future TODO is network tunneling for local printing and USB forwarding.USB forwarding is for sharing files on local usb memory. This soundsvery useful.
  • Developing tests for the KVM auto test
    • Lucas Meneghel Rodrigues
    • KVM auto test is fork of autotest. It runs 1 VM and runs tests in the VM. At the moment, it isn’t able to create multiple VMs and orchestrate them. Someone suggested to run KVM auto test in KVM. That sound good for nested virtualization.
  • Multi-threading QEMU
    • Anthony Liguori
    • This session should be about threading qemu, but the main theme was splitting maintainer ship.
    • KVM vcpu part is really threaded, but device emulation is single threaded. However the arbitration between KVM(virtualization) and TCG(embedded)is difficult. So he claimed to split out qemu maintainer ship and repository into libqemu-*.so.
  • QEMU’s new device model qdev
    • Markus Armbruster
    • He explained qemu new device model, qdev. I think it’s been a while since it was introduced so that it is already well understood. Nothing special.
  • Migration How to hop from machine to machine without losing state
    • Juan Quintela
    • This session is about new machine save/load framework called vmstate. It’s much cleaner than old ad-hoc save/load handlers. Live migration is difficult with device/ram hot plug.
  • Sheepdog: distributed storage system for QEMU
    • Kazutaka Morita
    • New part from the last presentation at LCA is benchmark with 256VM. It scaled well with 64 servers. Someone asked about disk scrub.
  • A Quest Against Time
    • Glauber Costa
    • Time is difficult issue to handle. Especially old OSes. The eventual solution is KVM clock(paravirtualize clock).
  • Paravirtualized DMA using IOMMU emulation
    • Joerg Roedel
    • This is about to minimize pinning guest pages. The current IOMMU can’t recover from DMA page fault, so that all guest pages must pinned. To overcome this restriction, paravirtualized guest DMA API.
  • Virtual Networking in KVM
    • Arnd Bergmann
    • Talk about open vswitch.

10th Aug.

LinuxCon Mini Summit: KVM-forum Day-2


  • virtio- and vhost- net

    • Michael S. Tsirkin
    • vhost-net is for accelerate network performance by kernelizing data path of virtio. The basic idea sounds very natural and promising. zerocopy and multiqueue are challenging.
  • KVM: PCI devcie assignment
    • Chris Wright
    • He talked about pci device assignement. There are many unsoleved issues. KVM as device driver idea sounded interesting. Future work includes VFIO, PRI and graphics.
  • WinKVM
    • Kazushi Takahashi
    • I’ve heard WinKVM, but this is the first time to watch the presentation. The idea is to use cygwin to create windows driver in PE executable. It sounds very forcible way.


11th Aug.

Linuxcon Day 3


  • BRTFS file system: status and Future
    • Chris Mason
    • vhost-net is for accelerate network performance by kernelizing data path of virtio. The basic idea sounds very natural and promising. zerocopy and multiqueue are challenging.
  • Linux Idle Power Checkup
    • Len Brown
    • This talk is about cpu idle. He showed many power usage measurement result.

12th Aug.

Linuxcon Day 4

  • Linux and Advanced Storage Technologies

    • Martin K. Petersen
    • He introduced recent storage technology and discussed issues realted to them. 4K sector size, discard(SCSI WRITE SAME, SCSI UMAP and ATA TRIM)and data integrity.
  • Improving Android Boot-up Time
    • Tim Bird
    • He tried to improve Android boot up time, but archived no improvement. Discussed many things he tried, but explained why it didn’t work.


プレゼン資料『PCI Express in QEmu』 (PDF:189 KB)
プレゼン資料『Network Bandwidth Isolation』 (PDF:460 KB)