Re: [Xen-devel] Xen 4.2 new features and status -- please help me make a list

[Andres Lagar-Cavilla <andres.lagarcavilla@xxxxxxxxx>]

On Sep 7, 2012, at 10:14 AM, Ian Campbell wrote:

> Hi all,
> 
> I've been trawling the mercurial logs looking for interesting new
> features to update http://wiki.xen.org/wiki/Xen_4.2_Feature_List and
> http://wiki.xen.org/wiki/Xen_Release_Features and have come up with a
> list of interesting things which I need to know more about before I can
> say stuff.
> 
> I've bcc'd people who I think might know about one or more of the
> following. If you do then please can you tell me:
> 
>      * What is the feature, what is the impact for the end user?
>      * What is it's status in 4.2? Is it a proof of concept, an
>        experimental feature, tech preview or a finished completed
>        feature.
>      * Is it new in 4.2? If it isn't new what was it's status in 4.1
>        and 4.0 (i.e. from the list in the previous item).
> 
> Of course if you know of a feature in 4.2 which isn't mentioned but
> which you think is worthwhile please let me know. I'm sure there are
> plenty which I missed.
> 
> Also feel free to edit the wiki instead....
> 
> TIA for your help.
> 
> Ian.
> 
> Nested Virtualisation: Allow HVM guests to use virtualisation hardware
> (e.g. Windows 7 compat mode)
>        Tech Preview, new in 4.2
> 
> vMSI: ? Emulated (or real?) MSIs for guests?
>        State? New in 4.2?
> 
> vMCE: Forward MCE (Machine Check Exceptions) to guests
>        New in 4.2? Preview or complete? I know improvements are pending
>        to migration in 4.3.
> 
> AMD OSVW: What is this?
>        Seems to be new in 4.2?
> 
> xenpaging: Page HVM guest pages to disk
>        Was marked as tech preview in 4.1 and earlier, still is?
> 
> memsharing: Sharing of HVM guest pages.
>        Was marked as tech preview in 4.1 and earlier, still is?

Both xenpaging and memsharing are functional as far as I am concerned. Intel 
EPT is the platform of choice. There are many reports of success on AMD insofar 
xenpaging goes, but I haven't gotten good traction with either 
xen{paging/sharing} on AMD. 

Please note that memsharing has been significantly overhauled both at an 
interface and internals level. It bears almost no resemblance to the 4.1 
release.

Xen{paging/sharing} still have border conditions in which domains are crashed. 
They are rare enough that I have not experienced them in practice. This is due 
to a need for more mature wait queue code in the hypervisor. The plan is to 
address this in 4.3.

Finally, mem-access has seen improvements and extensions. Now you can get a log 
of all memory accesses by a guest (if you so wished) using the n2rwx mode.

Cheers,
Andres

> 
> Intel HLE: What is this?
>        Seems to be new in 4.2?
> 
> Intel TRM: What is this?
>        Seems to be new in 4.2?
> 
> OVMF support for HVM guests.
>        New in 4.2, but disabled by default => Tech preview?
> 
> vPMU: Power Management?
>        New in 4.2?
> 
> ASID support:
>        4.2 gained an option to control this but I think it was
>        pre-existing. When was it first introduced? 4.1 or 4.0 or
>        before?
> 
> Core parking: Offlining CPUs for power reasons?
>        New in 4.2?
> 
> PV netboot: Network boot for PV guests
>        New in 4.2
> 
> 


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel