Xen Document Days/TODO

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Requested Documentation

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In progress (just need to double check whether finished)

A Xen Performance Tuning Guide

• Which workloads work for which virt mode. Network considerations. NUMA. VCPU Pinning. Etc.
• Examples from the KVM world: Guest perf tuning, KVM options affecting performance, Comprehensive guide covering pinning, caching, memory, huge pages, etc.
• Lars.kurth 19:50, 25 June 2012 (UTC) : Work has been done on Tuning. Not sure whether more needs to be done.
• Stefano 30 June 2012: The guide is in a decent state but I will keep improving it during the next doc days.
• Lars.kurth 15:54, 19 September 2012 (UTC): Needs a quick sanity check for Xen 4.2

Better XCP Overview Documentation

• Lars.kurth 08:02, 25 September 2012 (UTC) See XCP Overview & XCP Release Features - these need a little bit more work

Open work items

Better Statements on Compatibility

There seems to be some confusion in the wider Linxu community about XL/XM compatibility. Maybe some specific questions in an FAQ/the release notes. Also migration compatibility comes up often. Any articles related to compatibility should be listed in Category:Compatibility, which I am willing to clean up.

UEFI Secure Boot

Write a document on how to sign the xen binary for UEFI Secure Boot

Manpages for xe command

Write manpages for xe and it's 361 subcommands.

• A team led by Grant McWilliams and including Matthew Spah, Lisa Nguyen and Mike Webber is currently working on documenting the xe command and will continue to do so until completed. Moving the source repo to xen-org has been [proposed].

cpupools intro / howto

• George Dunlap I plan on doing this for September's doc day.

Describe the different ways, and necessary components, to create PVs using xl

Raised by mail by Matthias Blankenhaus (who is prepared to take the lead, but needs help): This document would describe the different ways, and necessary components that each way requires, to create PVs using xl. Right now there are at least the following cases:

• loopbacked vhds
  • single partition format
  • disk format
• qemu backed vhds
  • qcow / qcow2
• LVS backed image

This is not a complete list. Also the mileage of each case differs depending on the kernel features enabled in dom0/domu and also depending on the Xen version. Furthermore, certain format require additional infrastructure like the tap device.

All in all, this a complex topic that needs clarification. Doing this based on the lowest common denominator, xl, would clarify many things. In addition, baseline performance data on all of the above would help a great deal. Matthias volunteered to run the majority of needed perf tests

A Xen Security Guide

The different options in Xen for Security, trade-offs, how to set them up, how to test Xen for security and how to optimize for different scenarios

• Lars.kurth 09:48, 27 March 2012 (UTC): Category:Security contains some security related docs
• Lars.kurth 11:01, 4 April 2012 (UTC): It would be good if we could document a) XSM, b) Introspection API, c) Xen and SELinux in Dom0, d) Memory Access API (introduced in 4.1)
• User Docs that where migrating content would make sense and update such as (we can attach PDF's to the wiki now for starters, or we can use a conversion tool
  • http://bits.xensource.com/Xen/docs/user.pdf
• Lars.kurth 15:59, 19 September 2012 (UTC): Some good articles came out of XenSummit NA (these can be built upon). Got funding to document XSM.

Review and Update: xenpm usage recommendations

There is Xen power management and Xenpm command which may all be outdated. These should probably be reviewed and updated.

HOWTO : using xm trigger to poweroff or firing off NMIs

Howto on using xm trigger to poweroff or firing off NMIs.

HOWTO: Chain pypxeboot and pygrub

How to chain pypxeboot and pygrub

• Lars.kurth 10:35, 27 March 2012 (UTC): Is pypxeboot popular at all?
• Fheigl I added that. It is somewhat common, OVM 2 and OVM 3 rely on it for PXE installs. I'm not sure if xenpvnetboot is the same, or works. The use case is "you want to use the same installation server for Xen VMs and phys. servers. You want to be able to reinstall them based on PXE reply.
• Fheigl There is documentation for pypxeboot, but there is no (afaik) documentation for how pygrub is used as a fallback loader. We wasted many days just to get some hack that can't even load a newer kernel. Which sucks, in the end you spend more time/money making PV PXE boot work than you save by using virtualized servers.
• Fheigl Q3: How could it be popular given the state of documentation. <= Key issue to the left of this sentence.
• Lars.kurth 16:03, 19 September 2012 (UTC) : wondering whether this video contains what is needed

Done Recently

Clear up Xen TODO List

• Setting_boot_order_for_domUs
• XenDevelopmentProjects - although this will need maintaining
• Revamp http://wiki.xen.org/wiki/Xen_PCI_Passthrough. Should be more organized, easier to follow, less verbose, more thorough, and more up-to-date.
• Review and update http://en.wikipedia.org/wiki/Xen - in particular the "Host: Unix-like systems" is out-of-date. The Guest section is too.
• Make Host Install and Guest Install more useful
  • Lars.kurth Note: both pages share Template:Distro_Resources
  • Docs for many distros are missing: identify what docs are missing or out of date and put them on the todo list
• Feature Status Doc : Xen_Release_Features
• Xen Overview which explains the top level architectural features and options, trade-offs and links to examples tutorials that show how you set these up
• List i.e. stuff what to test after packaging. This would avoid the current state of affairs where most distros are infact broken w/re to Xen. See Distros
• Installation Guides: How to install on various distros. Tag with Category:Host Install and Category:Guest_Install.
• Tuning
• vcpu pinning (part of Tuning)

Developer Docs

Docs that need attention or are missing

• Make XAPI docs (built from source) available on xen.org
• PVOPS portal on xen.org - Konrad volunteered
• some more xenstore docs (i.e. recent python bindings that were sent to the -users list
• Using libxenstat python bindings (imo they're broken)
• More PV protocol docs (see recent patches to blkif.h for example)
• Document xenstore paths used by guests and toolstack etc

Wiki Maintenance

Fix articles that need attention

• Category:Contains_Needs_Action - Pages that need fixing
• Category:Contains_Needs_Formatting - Pages that need formatting
• Special:WantedPages - Missing pages (many may just need to be migrated), some may be obsolete

Review Categorization

We need to go through some of the categies on the http://wiki.xen.org/wiki/Main_Page and decise whether there are documents in each category that need to be highlighted in a trail, etc.

Loose ends on migration

• Migrate remaining wiki pages (see Wiki_Community/Migration_Instructions_from_Old_to_New_Xen_Wiki)