Tag Archives: tech talk

nbdkit / FOSDEM test presentation about better loop mounts for Linux

I’ve submitted a talk about nbdkit, our flexible pluggable NBD server, to FOSDEM next February. This is going to be about using NBD as a better way to do loop mounts in Linux.

In preparation I gave a very early version of the talk to a small Red Hat audience.

Video link: http://oirase.annexia.org/rwmj.wp.com/rjones-nbdkit-tech-talk-2018-11-19.mp4

Sorry about the slow start. You may want to skip to 2 mins to get past the intro.

Summary of what’s in the talk:

  1. Demo of regular, plain loop mounting.
  2. Demo of loop mounting an XZ-compressed disk image using NBD + nbdkit.
  3. Slides about how loop device compares to NBD.
  4. Slides about nbdkit plugins and filters.
  5. Using VMware VDDK to access a VMDK file.
  6. Creating a giant disk costing EUR 300 million(!)
  7. Visualizing a single filesystem.
  8. Visualizing RAID 5.
  9. Writing a plugin in shell script (live demo).
  10. Summary.



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libguestfs talk at FOSDEM

Big theatre!

The code examples are in this git repository (git clone git://git.annexia.org/git/libguestfs-talks.git)

Tech Talk is here.


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Tech Talk PSE 1.1.0

Tech Talk — the superior technical presentation software — is back!

(Not surprisingly this coincides with me doing a presentation at FOSDEM this weekend …)

The new version has been rebuilt around WebKit (all the work for this was done by Dan Berrange). Mozilla were never really serious about “MozEmbed”, and in practice it crashed all the time. WebKit (or KHTML as we like to call it) is built from the ground up for embedding and it is rock solid, so it was just better to switch.

Also in this development version is support for VTE, which is a simpler way to display terminal output. Any shell script called *.term is rendered in a built-in VTE terminal emulator. You can still use *.sh for shell scripts that you want to run during your presentation (eg. for using your own terminal, or just running arbitrary programs).

Tech Talk PSE is available from git or in Fedora Rawhide.

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Tech Talk PSE Wikipedia article, and new version

Unexpectedly Tech Talk PSE the superior presentation software for technical software demonstrations has got its own Wikipedia article (talk page). I knew nothing about it until I noticed the article appearing in the referer logs on my webserver. Appropriately it’s listed right above PowerPoint.

It seems like a good time to say that there’s a new minor version, 1.0.1. The only change is that we fixed the broken Next slide / Back buttons with a single line patch.

If you want to see me using Tech Talk PSE then skip to 30:00 in the Summit video.

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Presentation software sucks – introducing …

How many dull presentations have you been to where the presenter simply reads bullet points off slides?

FrobSoft Express 2.0 is:

  • up to 5% faster
  • supports Windows
  • XML enabled!

I’m giving a talk about libguestfs on 18th March and I hate reading out slides to people as much as I hate listening to presenters reading out slides to me. In every talk I’ve given in the last few years I have tried to keep my notes separate (written on paper in front of me, or memorized) from what is on the slides. Presentation software, such as the mighty, all-pervasive OpenOffice, doesn’t make this easy. Nor does it make it easy to demonstrate software in the middle of your talk. You end up having to switch away to another virtual desktop, where (hopefully) you’ve remembered to set up some xterms “su”‘d to root and “cd”‘d into the right directory. I usually need several virtual desktops set up like this so I can demonstrate different parts of the software, so I’m standing in front of an audience using [Alt][←] and [Alt][→] while I hastily try to remember which virtual desktop has the next stage of the talk.


Introducing “Tech Talk”. Actually, Tech Talk is too generic in Google, so we brainstormed adding extra words on the end until it became unique: Introducing “Tech Talk Platinum Supreme Edition!” (Tech Talk PSE).

The concept is simple. You create a directory and drop a mixture of HTML files and shell scripts in there:

$ ls
$ techtalk-pse

When Tech Talk PSE runs, it sorts the files numerically, and then displays the HTML ones (using Mozilla embedding) as slides and runs the shell script ones. Next and previous keys move through the slides, ensuring that your demonstrations [the shell scripts] run automatically at the right place in the talk.

Only files matching ^\d+(-.*)\.(html|sh)$ are considered, everything else is ignored. So you can style your HTML using stylesheets, include READMEs and Makefiles, and move common shell functionality into sourced shell files:

#!/bin/bash -
# Source common functions and variables.
source functions
# Pre-populate the shell history.
guestfish -a vm.img
# Open gnome-terminal.
exec $TERMINAL --geometry=+100+100

Tech Talk PSE itself doesn’t have to deal with rendering, which is pushed off to a browser, making it far more flexible, powerful and simpler than existing presentation software. This means you can show figures or play video in your presentation, or use Javascript to make your slides resolution-independent or to add animations. Additionally you can use any existing tool you want to write HTML. (If you’re like me, that tool will be emacs.)

You’ll be able to download Tech Talk PSE after my talk in two weeks time, or get early previews from my git repository. Requirements are Perl, Perl Gtk2 and Gtk2::MozEmbed.


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