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[Xen-devel] Xen 4.4 development update: Code freezing point reached

This information will be mirrored on the Xen 4.4 Roadmap wiki page:

(And I actually updated the wiki this time.)

The code "freezing point" is today; which means that starting today
non-bug fixes need a freeze exception to be included.

Remember our goal for the release:
 1. A bug-free release
 2. An awesome release
 3. An on-time release

Accepting a new feature may make Xen more awesome; but it also
introduces a risk that it will introduce more bugs.  That bug may be
found before the release (threatening #3), or it may not be found
until after the release (threatening #1).  Each freeze exception
request will attempt to balance the benefits (how awesome the
exception is) vs the risks (will it cause the release to slip, or
worse, cause a bug which goes un-noticed into the final release).

The idea is that today we will be pretty permissive, but that we will
become progressively more conservative until the first RC, which is
scheduled for 3 weeks' time (6 December).  After that, we will only
accept bug fixes.

Bug fixes can be checked in without a freeze exception throughout the
code freeze, unless the maintianer thinks they are particularly high
risk.  In later RC's, we may even begin rejecting bug fixes if the
broken functionality is small and the risk to other functionality is

Features which are currently marked "experimental" or do not at the
moment work at all cannot be broken really; so changes to code only
used by those features should be able to get a freeze exception
easily.  (Tianocore is something which would probably fall under

Features which change or add new interfaces which will need to be
supported in a backwards-compatible way (for instance, vNUMA) will
need freeze exceptions to make sure that the interface itself has
enough time to be considered stable.

These are guidelines and principles to give you an idea where we're
coming from; if you think there's a good reason why making an
exception for you will help us achieve goals 1-3 above better than not
doing so, feel free to make your case.

= Timeline =

Here is our current timeline based on a 6-month release:

* Feature freeze: 18 October 2013
* Code freezing point: 18 November 2013 <== WE ARE HERE
* First RC: 6 December 2013
* Release: 21 January 2014

Last updated: 18 November 2016

== Completed  ==

* Event channel scalability (FIFO event channels)

* Non-udev scripts for driver domains (non-Linux driver domains)

* Multi-vector PCI MSI (Hypervisor side)

* Improved Spice support on libxl
 - Added Spice vdagent support
 - Added Spice clipboard sharing support

* PHV domU (experimental only)

* Guest EFI booting (tianocore)

* kexec

* Testing: Xen on ARM

* Update to SeaBIOS

* pvgrub2 checked into grub upstream

== Resolved since last update ==

* credit scheduler doesn't update other fields when tslice updated from sysctl

== Open ==

* qemu-upstream not freeing pirq
 > http://www.gossamer-threads.com/lists/xen/devel/281498
 status: patches posted; latest patches need testing

* Race in PV shutdown between tool detection and shutdown watch
 > http://www.gossamer-threads.com/lists/xen/devel/282467
 > Nothing to do with ACPI
 status: Patches posted

* Supposed regression from a3513737 ("x86: allow guest to set/clear
 > MSI-X mask bit (try 2)"), as per
 > http://lists.xenproject.org/archives/html/xen-devel/2013-09/msg01589.html.

* qemu-traditional mis-parses host bus 8 as 0
 > http://bugs.xenproject.org/xen/bug/15

* xen_platform_pci=0 doesn't work with qemu-xen
 > http://bugs.xenproject.org/xen/bug/20

* xl does not support specifying virtual function for passthrough device
 > http://bugs.xenproject.org/xen/bug/22

* xl does not handle migrate interruption gracefully
  > If you start a localhost migrate, and press "Ctrl-C" in the middle,
  > you get two hung domains

* libxl / xl does not handle failure of remote qemu gracefully
  > Easiest way to reproduce:
  >  - set "vncunused=0" and do a local migrate
  >  - The "remote" qemu will fail because the vnc port is in use
  > The failure isn't the problem, but everything being stuck afterwards is

* HPET interrupt stack overflow (when using hpet_broadcast mode and MSI
capable HPETs)
  owner: andyh@citrix
  status: patches posted, undergoing review iteration.

== Backlog ==

=== Testing coverage ===

* new libxl w/ previous versions of xl

* Host S3 suspend
 @bguthro, @dariof

* Default [example] XSM policy
 @Stefano to ask Daniel D

* Storage driver domains

* HVM pci passthrough

* PV pci passthrough
 @konrad (or @george if he gets to it first)

* Network driver domains

* Nested virt?
 @intel (chased by George)

* Fix SRIOV test (chase intel)

* Fix bisector to e-mail blame-worthy parties

* Fix xl shutdown

* stub domains

* performance benchmarks

=== Meta-items (composed of other items) ===

* Meta: PVIO NUMA improvements
 - NUMA affinity for vcpus (4.4 possible)
 - PV guest NUMA interface (4.4 possible)
 - Sensible dom0 NUMA layout
 - Toolstack pinning backend thread / virq to appropraite d0 vcpu
 - NUMA-aware ballooning

* xend still in tree (x)
 - xl list -l on a dom0-only system
 - xl list -l doesn't contain tty console port
 - xl Alternate transport support for migration*
 - xl PVSCSI support
 - xl PVUSB support

=== Big ticket items ===

* PVH mode (w/ Linux)
  owner: mukesh@oracle, george@citrix
  status (Linux): Acked, waiting for ABI to be nailed down
  status (Xen): Initial version checked in, still nailing down interface

* Update to qemu 1.6
  owner: Anthonyper
  status: In staging, still working out a bug in the VMX code

* Live Migration Support
  owner: Jaeyong Yoo <jaeyong.yoo@xxxxxxxxxxx>
  status: v5 posted, looking good for code freeze

* ARM64 guest
  owner: IanC
  status: v3 posted, v4 in progress. looking good.

* SWIOTLB (kernel side thing)
  owner: Stefano
  status: Pull request sent.

* soft affinity for vcpus (was NUMA affinity for vcpus)
    owner: Dario
    status: v2 posted

* PV guest NUMA interface
    owner: Elena
    status: v3 posted

* libvirt/libxl integration (external)
 - owner: jfehlig@suse, dario@citrix
 - patches posted (should be released before 4.4)
  - migration
  - PCI pass-through
 - In progress
  - integration w/ libvirt's lock manager
  - improved concurrency

* xl USB pass-through for HVM guests using Qemu USB emulation
  prognosis: Good if extended
  owner: George
  status: v6 patch series posted

* libxl: Spice usbredirection support for upstream qemu
 owner: fabio@M2R
 status: I'll post new patch version shortly

* libxl: usb2 and usb3 controller support for upstream qemu
 owner: fabio@M2R
 status: patch v5 posted, tested and working, awaiting reviews

* libxl network buffering support for Remus
   status: patches posted
   prognosis: fair

* Disk: indirect descriptors
   owner: roger@citrix
   status: Linux side in 3.11, Xen-side patch posted

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