The document summarizes updates to the Xen Hypervisor project, including: - Plans for future stable releases in late 2011 and early 2012. - Improvements to HVM device model and BIOS support in Qemu. - Dom0 Linux kernel support now in Linux 3.0. - Work to optimize performance for PV guests through lightweight HVM containers.

1. Xen Hypervisor Update
Keir Fraser - xen.org
Sponsored by:
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2. Release plans ®
• Current stable releases: 4.0.2 and 4.1.1
• New point releases planned for later this month
• Ongoing strategy:
– Maintain two stable branches at a time
– Quarterly releases from stable branches
– Around nine months between major releases
– Xen 4.2 likely in early 2012
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8/11/2011

3. HVM Device Model & BIOS
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• Xen support is now in upstream Qemu
– Mapcache, VGA dirty bits, unplug protocol, …
– New development branch announced on xenbits
– We can now take advantage of new or upcoming Qemu
upstream features: PCI Express, USB EHCI/XHCI, Firewire
• Associated work to extend our virtual BIOS support
– SeaBIOS is legacy BIOS supported by upstream Qemu
– OVMF (EDK II / Tianocore) for UEFI support
• Faster Windows boot
• Supported by Mac OS X out of the box
• May be needed for platform certification in the future
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4. Linux 3.0
®
• Dom0 support is now in upstream Linux
• Just in time for Linux 3.0 !
• This will naturally trickle down to become a common
distro feature, with no need for maintaining an old
kernel version, or porting the old dom0 patchset
• Everything needed to run a full Xen system is in Linux
3.0
• Thanks to Jeremy, Konrad, and many others
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5. Guest performance
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• X86/64 PV guests suffer poor syscall performance
• There are hardware features that optimise guest
performance that are only available to HVM guests
• Solution: optionally run PV guests in a lightweight
HVM container
• Mukesh Rathor (Oracle) has a prototype running
with promising results
• Expected to be ready for inclusion well in time for
Xen 4.2.
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6. Nested virtualization
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• Allows a fully-virtualized (HVM) guest to itself detect
and use the HVM processor features
– VMX-on-VMX (Intel); SVM-on-SVM (AMD)
• Uses:
– Client virtualization experience
– Embedded hypervisor
– Hypervisor testing 
• Recently applied to 4.2 development branch
– Needs more testing (please!)
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7. Toolstack (libxenlight)
®
• Libxenlight now used by other clients than XL
– Libvirt
– (In progress) xapi (XCP)
• API improvements are being made to make
libxenlight better suit a wider range of client users
• Better Qemu integration: QMP support
– Will be used to issue run-time commands to Qemu
– Patches recently posted to xen-devel
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8. ARM
®
• Samsung published an ARM port in 2008
• Working to sync with Xen development tree
– And get ARM support integrated with upstream
• Initial support for PV guests
• HVM support also in the pipeline
– Using new virtualisation extensions in Cortex A15
• Hopefully this will be integrated for Xen 4.2
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9. Other stuff
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• Remus – replication & failover for high availability
– Shriram Rajagopalan @ UBC is kicking it into shape
• Guest-memory automatic sharing and paging
– In preview since 4.0
– Various folks working on fixing bugs and tricky corner cases
• RAS
– Ongoing improvements to graceful handling of hardware
faults
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10. Managing development
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• Use the developer mailing lists
– xen-devel@lists.xensource.com
– Requests for comments
– Announcements of dev plans
– Patches posted for comment, review and checkin
• Use the wiki
– http://wiki.xen.org/
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