Xen 4.2 TODO / Release Plan

[Ian Campbell <Ian.Campbell@citrix.com>]

Plan for a 4.2 release:
http://lists.xen.org/archives/html/xen-devel/2012-03/msg00793.html

The time line is as follows:

19 March        -- TODO list locked down
2 April         -- Feature Freeze
                                                << WE ARE HERE
Mid/Late May    -- First release candidate
Weekly          -- RCN+1 until it is ready

The updated TODO list follows. Per the release plan a strong case will
now have to be made as to why new items should be added to the list,
especially as a blocker, rather than deferred to 4.3.

A lot of new DONE items. The big remaining items are
the hotplug script series and asynchronisation of migration.

If you are aware of any bugs which must/should be fixed for 4.2 then
please reply to this thread (otherwise I may not remember to pick them
up next week)

Other than that I think we should consider the freeze to be in full
effect and the bar to entry to 4.2 to be very high.

hypervisor, blockers:
      * Performance regression due to contention on p2m lock. (Tim,
        Andres, DONE) 
 
tools, blockers:
      * libxl stable API -- we would like 4.2 to define a stable API
        which downstream's can start to rely on not changing. Aspects of
        this are:
              * libxl_wait_for_free_memory/libxl_wait_for_memory_target.
                Interface needs an overhaul, related to
                locking/serialization over domain create (deferred to
                4.3). IanJ to add note about this interface being
                substandard but otherwise defer to 4.3.
              * libxl_*_path. Majority made internal, only configdir and
                lockdir remain public (used by xl). (IanC, to consider
                moving the two reamining into xl instead of libxl)
              * Interfaces which may need to be async:
                      * libxl_domain_suspend. Move
                        xc_domain_save/restore into a separate process
                        (IanJ, RFC posted).
                      * libxl_device_{disk,nic,vkb,add,pci}_add (and
                        remove?). Roger Pau Monné fixes disk as part of
                        hotplug script series and adds infrastructure
                        which should make the others trivial. (Roger,
                        WIP)
                      * libxl_cdrom_insert. Should be easy once
                        disk_{add,remove} done. Nobody is looking at
                        this?
                      * libxl_device_disk_local_{attach,detach}. Become
                        internal as part of Stefano's domain 0 disk
                        attach series (already tracked below, "Domain 0
                        block attach & general hotplug", will remove
                        this entry instance from next weeks list in
                        favour of that one)
      * xl compatibility with xm:
              * [BUG] cannot create an empty CD-ROM driver on HVM guest,
                reported by Fabio Fantoni in
                <4F9672DD.2080902@tiscali.it>
              * does not automatically try to select a (set of) node(s)
                on which to create a VM and pin its vcpus there. (Dario
                Faggioli, patches posted)
              * `cpus=[2,3]` to select specific mapping vcpu0-->pcpu2,
                vcpu1-->pcpu3 as xm does. (Dario Faggioli, patches
                posted and reviewed, will repost)
      * [BUG] Spurious CPU params error message when starting a domain,
        e.g. "Cpu weight out of range, valid values are within range
        from 1 to 65535". ("George will do it if no one else steps up")
      * More formally deprecate xm/xend. Manpage patches already in
        tree. Needs release noting and communication around -rc1 to
        remind people to test xl.
      * xl to refuse to run if xend is running, Roger Pau Monné (DONE)
      * Domain 0 block attach & general hotplug when using qdisk backend
        (need to start qemu as necessary etc) (Stefano S, patches
        posted, needs updates)
      * Improved Hotplug script support (Roger Pau Monné, patches
        posted)
      * Block script support -- follows on from hotplug script (Roger
        Pau Monné)
      * xs.h -> xenstore.h. Should do this for 4.2 rather than have
        distros carry their own patches. (Ian C, DONE)
      * Adjustments needed for qdisk backend to work on non-pvops Linux.
        (Jan Beulich)

hypervisor, nice to have:
      * PoD performance improvements (George Dunlap)
      * IRQ problem for which debugging code got added by c/s
        24707:96987c324a4f. I have a tentative adjustment to this which
        I would hope to at least eliminate the bad consequences of
        crashing the hypervisor (converting the unsolicited
        PIC-originated IRQ into a spurious one). I'll submit as soon as
        I got to test this a little, particularly also on an old box
        without APIC. (Jan Beulich)

tools, nice to have:
      * Upstream qemu feature patches:
              * Upstream qemu PCI passthrough support (Anthony Perard,
                awaiting qemy upstream review)
                      * Upstream qemu is frozen for their next release.
                        Unlikely that these will be accepted in the next
                        few weeks. Defered until 4.3 (therefore DONE in
                        this context)
              * Initial xl support for Remus (memory checkpoint,
                blackholing) (Shriram, DONE)
      * xl compatibility with xm:
              * xl support for autospawning vncviewer (vncviewer=1 or
                otherwise) (Goncalo Gomes, DONE)
      * Directory usage in libxl (Bastian, as part of Debian packaging).
        Defer to 4.3, therefore DONE in this context.
              * dumps in /var/xen: wtf?
                      * Bastian: "The FHS defines /var/crash for system
                        crash dumps, but it is not used everywhere. So I
                        would use /var/lib/xen/dump or so."
              * user data files in /var/lib/xen:
                      * What are the guarantees given for this files?
                      * Bastian: "I don't think rebooting the control
                        domain without rebooting Xen will work right
                        now. So /var/run is the correct location."
              * /var/run/libxl for temporary files
                      * "$TMPDIR or the fallback /tmp is the correct
                        location."
      * xl commands to help rebind pci devices to pciback.  (George
        Dunlap, DONE)
      * libxl: Add API to retrieve domain console tty (Bamvor Jian
        Zhang, patches posted)



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