Xen Developer Summit BoF Notes : Seeding a Xen + Android / Embedded ecosystem BoF

[Lars Kurth <lars.kurth@xen.org>]

Hi all,

this is a copy of the notes I took at the Bof. I may have missed quite a 
few pices here. I also don't know who was at the BoF (we had about 40 
people there) . I have an action to make this thread available on 
http://xenproject.org/component/content/article/9-uncategorised/159-xen-project-developer-summit-2013-videos-and-presentations.html 
and to a mailshot to summit attendees. I also added these at 
http://wiki.xenproject.org/wiki/XPDS13_BoF_Notes_:_Seeding_an_Android_and_Embedded_ecosystem

Please feel free to add stuff.

Regards
Lars

== Platforms ==
# The overall agreement in the BoF was that Android on Xen should be 
platform agnostic
# aka support ARM as well as Intel (e.g. many Android tablets in China 
are Intel based)

== Missing Pieces for a complete Android system on top of Xen ==
# Backend ION memory allocator (manages allocation of additional 
buffers). My understanding that what was needed is an ION memory 
allocator for PV drivers
## Samsung noted that a ION PV allocator may be need to be specialized 
for a particular SOC
## There was a bit of debate on whether it would be valuable to have a 
reference ION PV allocator
# Wrapper user space Device Drivers for Graphic, Sound, USB, Giros, GPS, 
etc.
## These are not Linux drivers but user space drivers
## In most cases these will be shims, but some may be device specific
## A common place in the Xen Project (or even better in Android) where 
these could be put would help everyone
## The Xen Project could host a repo initially; as more momentum builds 
the case to approach Google is likely to increase

== Pieces missing for Embedded (non-Android) ==
# Xen Dom0 support in [https://openwrt.org/ OpenWrt]; 
[http://wiki.openwrt.org/doc/howto/xen DomU] support exists
# Soft-Real-time support - note that this was in the original Xen ARM 
port - see [[Xen_ARM_(PV)]]. But it didn't make it across to the Xen on 
ARM support. Also see a related more general thread at 
[http://lists.xenproject.org/archives/html/xen-devel/2013-11/msg02536.html 
xen-devel].
# Hard-Real-time support: a US government standard / RT kernel / OS was 
mentioned. In my notes it says '''Arine7''' ... but this is obviously 
wrong as google does not find anything.
# Longer term: GPU virtualization - Video Card fragmenbtation is a huge 
issue
## Establish a list of GPUs vendors (note that this would be a very long 
list)
## Wait for Intel and Samsung to start submitting patches for their 
technology (see  [http://www.youtube.com/watch?v=Km6gBnIqaWo 
<http://www.youtube.com/watch?v=Km6gBnIqaWo&feature=youtu.be>] and 
[http://www.youtube.com/watch?v=P5c7B9lk_Q0])
## Are there any software alternatives?
## Stefano (I think) made the point that the Android GPU interface would 
lend itself for a neat standard interface for GPU virt in Xen

== Mechanics of Bootstrapping a Community ==
# Lists
## The general consensus was that it would be a bad idea to create a new 
list. Discussions should happen on xen-devel
## However some attendees were concerned about the volume of traffic
## Threads related to ANDROID on xen-devel should be tagged with ANDROID

[Aside: I am wondering, whether a more low-volume list for bigger and 
longer-term developer discussions may be helpful. We have done this in 
the past and all the lists in question (IA64, ARM, ...), but over time 
these lists had to be culled when the developed features became 
mainstream. There have also been some discussion recently about the 
amount of traffic on xen-devel becoming a little painful. I am just 
putting this one up for debate, but this would probably grant a separate 
discussion. ]

# Meetings / Calls
## A monthly or less frequent open call would help
## Action Lars: write up minutes {{Tick}}, send out to all attendees and 
get the ones who'd be interested to reply whether'd be interested

== Missing non-code pieces to speed up adoption ==

# Sharing of information andf helping each other
## This comes back down to the list / meeting /calls part

# Lack of documentation
## Step 1: create an embedded and android category on the wiki (and post 
these notes). Created http://wiki.xenproject.org/wiki/Category:Embedded 
and http://wiki.xenproject.org/wiki/Category:Android {{Tick}}
## Somebody to Volunteer to create a '''Getting Started with Xen on 
Android''' on the wiki
## A Hackathon hosted by a vendor that cares about Android / Embedded in 
2014
## Have a central place / repo for Android user space drivers
### Open Question (for Android experts): is there something like an 
upstream for Android user space drivers today?
### How does one contribute (assuming such a place exists)?