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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libguestfs for RHEL 7.5 preview

As usual I’ve placed the proposed RHEL 7.5 libguestfs packages in a public repository so you can try them out.

Thanks to Pino Toscano for doing the packaging work.

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Great new changes coming to nbdkit

Eric Blake has been doing some great stuff for nbdkit, the flexible plugin-based NBD server.

  • Full parallel request handling.
    You’ve always been able to tell nbdkit that your plugin can handle multiple requests in parallel from a single client, but until now that didn’t actually do anything (only parallel requests from multiple clients worked).
  • An NBD forwarding plugin, so if you have another NBD server which doesn’t support a feature like encryption or new-style protocol, then you can front that server with nbdkit which does.

As well as that he’s fixed lots of small bugs with NBD compliance so hopefully we’re now much closer to the protocol spec (we always check that we interoperate with qemu’s nbd client, but it’s nice to know that we’re also complying with the spec). He also fixed a potential DoS where nbdkit would try to handle very large writes which would delay a thread in the server indefinitely.

Also this week, I wrote an nbdkit plugin for handling the weird Xen XVA file format. The whole thread is worth reading because 3 people came up with 3 unique solutions to this problem.

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Fedora 27 virt-builder images

Fedora 27 has just been released, and I’ve just uploaded virt-builder images so you can try it right away:

$ virt-builder -l | grep fedora-27
fedora-27                aarch64    Fedora® 27 Server (aarch64)
fedora-27                armv7l     Fedora® 27 Server (armv7l)
fedora-27                i686       Fedora® 27 Server (i686)
fedora-27                ppc64      Fedora® 27 Server (ppc64)
fedora-27                ppc64le    Fedora® 27 Server (ppc64le)
fedora-27                x86_64     Fedora® 27 Server
$ virt-builder fedora-27 \
      --root-password password:123456 \
      --install emacs \
      --selinux-relabel \
      --size 30G
$ qemu-system-x86_64 \
      -machine accel=kvm:tcg \
      -cpu host -m 2048 \
      -drive file=fedora-27.img,format=raw,if=virtio &

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nbdkit finally supports TLS (encryption)

nbdkit is a liberally licensed NBD server which a stable plugin API for serving disks from unconventional sources.

Finally I got around to adding TLS (encryption and authentication) support. The support is complete and appears to interoperate with QEMU. It also supports a certificate authority, client certificate verification, certificate revocation, server verification (by the client), and configurable algorithms.

Actually using TLS with NBD is no easy matter. It takes a few pages of instructions just to explain how to set up the public-key infrastructure. On the client (QEMU) side, the command line parameter for connecting to a TLS-enabled NBD server is lengthy.

Then there’s the question of how you ensure TLS is being used. In nbdkit as in other NBD servers you can either turn on TLS in which case it’s used when the client requests it, or you can require TLS. In the latter case nbdkit will reject non-TLS connections (thus ensuring TLS is really being used), but most clients won’t be able to connect to such a server.

As usual, where SSH got it right, SSL/TLS/HTTPS got it all horribly wrong.


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Tip: Changing the qemu product name in libguestfs

20:30 < koike> Hi. Is it possible to configure the dmi codes for libguestfs? I mean, I am running cloud-init inside a libguestfs session (through python-guestfs) in GCE, the problem is that cloud-init reads /sys/class/dmi/id/product_name to determine if the machine is a GCE machine, but the value it read is Standard PC (i440FX + PIIX, 1996) instead of the expected Google Compute Engine so cloud-init fails.

The answer is yes, using the guestfs_config API that lets you set arbitrary qemu parameters:

         'type=1,product=Google Compute Engine')

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Downloading all the 78rpm rips at the Internet Archive

I’m a bit of a fan of 1930s popular music on gramophone records, so much so that I own an original early-30s gramophone player and an extensive collection of discs. So the announcement that the Internet Archive had released a collection of 29,000 records was pretty amazing.

[Edit: If you want a light introduction to this, I recommend this double CD]

I wanted to download it … all!

But apart from this gnomic explanation it isn’t obvious how, so I had to work it out. Here’s how I did it …

Firstly you do need to start with the Advanced Search form. Using the second form on that page, in the query box put collection:georgeblood, select the identifier field (only), set the format to CSV. Set the limit to 30000 (there are about 25000+ records), and download the huge CSV:

$ ls -l search.csv
-rw-rw-r--. 1 rjones rjones 2186375 Aug 14 21:03 search.csv
$ wc -l search.csv
25992 search.csv
$ head -5 search.csv

A bit of URL exploration found a fairly straightforward way to turn those identifiers into directory listings. For example:


What I want to do is pick the first MP3 file in the directory and download it. I’m not fussy about how to do that, and Python has both a CSV library and an HTML fetching library. This turns the CSV file of links into a list of MP3 URLs. You could easily adapt this to download FLAC files instead.


import csv
import re
import urllib2
import urlparse
from BeautifulSoup import BeautifulSoup

with open('search.csv', 'rb') as csvfile:
    csvreader = csv.reader(csvfile, delimiter=',', quotechar='"')
    for row in csvreader:
        if row[0] == "identifier":
        url = "" % row[0]
        page = urllib2.urlopen(url).read()
        soup = BeautifulSoup(page)
        links = soup.findAll('a', attrs={'href': re.compile("\.mp3$")})
        # Only want the first link in the page.
        link = links[0]
        link = link.get('href', None)
        link = urlparse.urljoin(url, link)
        print link

When you run this it converts each identifier into a download URL:

Edit: Amusingly WordPress turns the next pre section with MP3 URLs into music players. I recommend listening to them!

$ ./ | head -10

And after that you can download as many 78s as you can handle 🙂 by doing:

$ ./ > downloads
$ wget -nc -i downloads


I only downloaded about 5% of the tracks, but it looks as if downloading it all would be ~ 100 GB. Also most of these tracks are still in copyright (thanks to insane copyright terms), so they may not be suitable for sampling on your next gramophone-rap record.

Update #2

Don’t forget to donate to the Internet Archive. I gave them $50 to continue their excellent work.


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