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SiFive unleashed board



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nbdkit filters

nbdkit is our toolkit for creating Network Block Device (NBD) servers from “unusual” data sources. nbdkit was already configurable by writing simple plugins in several programming languages. Last week Eric Blake and I added a nice new feature: You can now modify existing plugins by placing “filters” in front of them.

A plugin might do something simple like serve a local file from disk or complicated like bridging to VMware servers. A filter can modify this by:

(You can also layer filters to arbitrary depth)

nbdkit 1.1.27 has three simple filters, and 1.1.28 will include two more, and you can write your own although (unlike plugins) filters do not yet have a stable ABI and we haven’t decided if we will offer a stable ABI in future.

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Intel NUC

I’ve been looking for replacements for my HP Microservers which according to this blog are now nearly 7 years old!. Although still going (sort of) strong: one of them failed completely, and another has developed a faulty cache manifested by random 32 byte wide web server corruption (yes, it’s also my main web server …)

My virtualization cluster is also coming up to 4 years old, and while it works fine it turns out that running servers without cases isn’t such a good idea because they generate large amounts of RF interference.

So you can tell that my current computing setup is held together with string and sticky tape. Can I make a nicer system based on a pile of NUCs? I bought 1 NUC for testing:


The total cost (including tax and delivery) was £583.96 from I also specced up a similar system with an M.2 SSD which would have been about £670. (An ideal system would have both M.2 SSD and a hard disk but that gets even more expensive.) The NUC model is NUC7i5BNH and the Wikipedia page is absolutely essential for understanding the different models.

Enough talk, how well does it work? To start off with, really badly with the NUC regularly hanging hard. This was because of a faulty RAM module, a problem I’ve had with the Gigabyte Brix before. Because of that, I’m only running with one 8 GB module:


It has two real cores with hyperthreading. The cores are Kaby-Lake Intel(R) Core(TM) i5-7260U CPU @ 2.20GHz.

The compile performance is reasonable, not great, as you’d expect from an Intel i5 processor.


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RISC-V Tokyo

Today (was) RISC-V Day 2017 Tokyo at the University of Tokyo (programme in English, more information in English). My colleague Wei Fu gave a talk on the status of Fedora on RISC-V. I hope it was recorded somewhere. If it appears online I’ll update this post.

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FOSDEM 2018 Virtualization devroom

The programme has been published here. Looks pretty good! Lots of Kubernetes/KubeVirt this year.

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Keeping a work notebook

There has been some discussion on HN of using a logbook or notebook. I’ve used a work notebook on paper for about 20 years. Here are the ones from the last 8 years (minus the one I’m currently using):


Years ago Red Hat even had their own branded notebooks. I nicked one from the office supply cabinet and they seem to have stopped making them:


The older books had blank pages. These notes from 2010 record a list of bugs (tick marks for done/fixed items) and the initial design of guestfs-browser:


Unfortunately unlined pages don’t work well for me because I have pretty terrible handwriting. I’ve moved to using lined notebooks now as you can see by comparing these two pages from 2011 and 2014 respectively:

My ideal notebook is the Oxford Black n’ Red A5 Matt Casebound Hardback Notebook, Ruled 192 Pages, and my ideal pen is the UM-153S Signo Impact Gel Pen:


Most of the pages are scribbled notes from meetings. If you saw me furiously scribbling at the KVM Forum last month, then this is what I was writing.


I find it really helpful to remember the contents of meetings and what to do. Asterisks mean ideas for future research or work. Ticks are items which have been done.

The number of doodles is not necessarily related to the boredom in the meeting!

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make -j46 kernel builds on Qualcomm Amberwing


Really nice doing make -j46 kernel builds on Qualcomm’s insanely fast ARM-based Amberwing server.

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