[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Xen-devel] Xen 4.2 Release Plan / TODO
Plan for a 4.2 release:
The time line is as follows:
19 March -- TODO list locked down
2 April -- Feature Freeze << WE ARE HERE
Mid/Late April -- 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.
We have now entered Feature Freeze. Patches which have been posted
before or which address something on the list below are still acceptable
(for now, we will gradually be getting stricter about this), everything
else will be deferred until 4.3 by default.
* 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
* Safe fork vs. fd handling hooks. Involves API changes
(Ian J, patches posted)
* locking/serialization, e.g., for domain creation. As of
now, nothing is provided for this purpose, and
downstream toolstacks have to put their own mechanisms
in place. E.g., xl uses a fcntl() lock around the whole
process of domain creation. It should OTOH be libxl job
to offer a proper set of hooks --placed at the proper
spots during the domain creation process-- for the
downstreams to fill with the proper callbacks. (Dario
* agree & document compatibility guarantees + associated
technical measures (Ian C, patches posted)
* xl compatibility with xm:
* feature parity wrt driver domain support (George Dunlap)
* xl support for "rtc_timeoffset" and "localtime" (Lin
Ming, Patches posted)
* More formally deprecate xm/xend. Manpage patches already in
tree. Needs release noting and communication around -rc1 to
remind people to test xl.
* Domain 0 block attach & general hotplug when using qdisk backend
(need to start qemu as necessary etc) (Stefano S)
* file:// backend performance. qemu-xen-tradition's qdisk is quite
slow & blktap2 not available in upstream kernels. Need to
consider our options:
* qemu-xen's qdisk is thought to be well performing but
qemu-xen is not yet the default. Complexity arising from
splitting qemu-for-qdisk out from qemu-for-dm and
running N qemu's.
* potentially fully userspace blktap could be ready for
* use /dev/loop+blkback. This requires loop driver AIO and
O_DIRECT patches which are not (AFAIK) yet upstream.
* Leverage XCP's blktap2 DKMS work.
* Other ideas?
* In general we should recommend blkback (e.g.
with LVM) since it always out performs other
solutions, although at the expense of
flexibility regarding image formats.
Stefano has done a lot of work here and has proposed some
performance improvements for qdisk in both qemu-xen and
qemu-xen-traditional which make them a plausible alternative for
* Improved Hotplug script support (Roger Pau MonnÃ, patches
* Block script support -- follows on from hotplug script (Roger
hypervisor, nice to have:
* solid implementation of sharing/paging/mem-events (using work
queues) (Tim Deegan, Olaf Herring et al -- patches posted)
* "The last patch to use a waitqueue in
__get_gfn_type_access() from Tim works. However, there
are a few users who call __get_gfn_type_access with the
domain_lock held. This part needs to be addressed in
* Sharing support for AMD (Tim, Andres).
* PoD performance improvements (George Dunlap)
tools, nice to have:
* Configure/control paging via xl/libxl (Olaf Herring, lots of
discussion around interface, general consensus reached on what
it should look like. Olaf has let me know that he is probably
not going to have time to do this for 4.2, will likely slip to
4.3 unless someone else want to pick up that work)
* Upstream qemu feature patches:
* Upstream qemu PCI passthrough support (Anthony Perard,
* Upstream qemu save restore (Anthony Perard, Stefano
Stabellini, qemu patches applied, waiting for libxl etc
side which has been recently reposted)
* Nested-virtualisation. Currently "experimental". Likely to
release that way.
* Nested SVM. Tested in a variety of configurations but
still some issues with the most important use case (w7
XP mode)  (Christoph Egger)
* Nested VMX. Needs nested EPT to be genuinely useful.
Need more data on testedness etc (Intel)
* Initial xl support for Remus (memory checkpoint, blackholing)
(Shriram, patches reposted recently, was blocked behind qemu
save restore patches which are now in)
* xl compatibility with xm:
* xl support for autospawning vncviewer (vncviewer=1 or
otherwise) (Goncalo Gomes, patches posted)
* support for vif "rate" parameter (Mathieu GagnÃ, patches
* expose PCI back "permissive" parameter (George Dunlap)
Xen-devel mailing list