catonmat.net: The Busy Beaver Problem

DatabaseError: file is encrypted or is not a database

Hmn, so let’s check the trac migration guide which advises you to first export the sqlite database with sqlite3 in a plain SQL file. Not much luck here either, the result is an empty database:

# sqlite3 trac.db .dump
BEGIN TRANSACTION;
COMMIT;


The reason is the trac installation in Etch was using the python-sqlite-1.0.1 back-end which uses the SQLite 2 format while in Lenny there is python-pysqlite2-2.4.1 which only knows about SQLite 3.

The conversion from SQLite 2 to 3 can be done by first exporting the database with the sqlite tool and then re-importing it with sqlite3:

# sqlite trac.db .dump | sqlite3 trac3.db


More infos about this can be found at the trac upgrade notes from 0.8.x to 0.9.

Finally your trac installation should work again as usual.

For using Xen virtualization a separate patchset always had to be applied to the hypervisor and also the paravirtualized Linux kernel. Because of this it wasn’t always easy to migrate physical servers into virtual one’s, especially when requiring a special kernel version or another profound Linux patchset.

What is paravirt_ops?
Paravirt_ops is a generic kernel structure that represents an interface to a virtualization hypervisor. It allows the kernel to run natively on the hardware but also virtual on a hypervisor. Since kernel 2.6.23 paravirt_ops support for Xen is integrated into the vanilla kernel and since then also support for VMI (VMware) and KVM was added. It is a first step to integrate full Xen compatibility into the mainline kernel tree. Today, with kernel 2.6.27, Xen paravirt_ops support exists at least for the x86 and x86_64 architecture.

How can I use the vanilla kernel as Xen domU?
If you build the kernel by yourself, like every real man does, you have to activate the following features. Build the support directly into the kernel that you don’t have to fiddle around with an initramfs.


Processor type and features --->
[*] Paravirtualized guest support —>
— Paravirtualized guest support
[*] Xen guest support
…
[*] PAE (Physical Address Extension) Support

Device Drivers --->
[*] Block devices —>
<*> Xen virtual block device support
…
[*] Network device support —>
<*> Xen network device frontend driver
…
Character devices —>
[*] Xen Hypervisor Console support

Now we’re nearly done with it. After compiling the kernel we need to do some small changes concerning the console redirection in the baselayout of the Linux guest. In the future the distributions will likely prepare this for us.

Add hvc0 device node:

cd /dev
mknod hvc0 c 229 0
chown root:tty hvc0
chmod 600 hvc0

To change default console to hvc0 you have to edit the /etc/inittab. If not done already, disable all the other virtual consoles:

co:12345:respawn:/sbin/agetty 38400 hvc0 vt100-nav
#2:23:respawn:/sbin/agetty 38400 tty2
#3:23:respawn:/sbin/agetty 38400 tty3
...

Finally permit login on the hvc0 console by adding it to /etc/securetty.

Now we should be able to boot our paravirt_ops system on real hardware the same as on a Xen hypervisor. However compared with a Xen-patched paravirtualized kernel, the paravirt_ops kernel doesn’t support special features like framebuffer support or live migration.

Links:

You don’t believe me… read yourself:
www.chinapost.com.tw: ‘3D virtual guinea pig’ to be used for drug development

The Canadian photographer and cameraman Edward Burtynsky attracted a lot of attention by his longterm work about how mankind changes the natural landscapes. The movie “Manufactured Landscapes” is showing us how industrialization in China looks like. He did choose China because it more and more becomes the factory of the world with all its negative consequences.

But compared to the movie “An Inconvenient Truth” by Al Gore about the global warming this movie does not rate the human acting. “Manufactured Landscapes” does not explain or discuss the destruction of nature it only shows it. Exactly this neutrality of the film-makers does lead to a speechlessness. You cannot totally accuse what you see because we depend on it and we provoke it with our economy. But on the other site it irreversibly destroys what has been on earth a long time before mankind.

The mixture of pictures and videos is underlaid with cold music and industrial noise. Sometimes there are short interviews, for example with a Chinese girl who assembles about 400 fuses a day, since six years. Or with an official of a coal mine trying to prevent the artist from filming their facility. You see the construction site of the Three Gorges Dam and the people destroying their own houses because their city will be flooded by this project. You see girls destructing our Computer waste for regaining the materials. But they cannot drink their ground water anymore because it is full of heavy metal residues. The movie shows the city of Shanghai which has to assimilate an increase in population of more than a million people per year. These are definitely other dimensions than we can even imagine here…

If I made you curious now you can watch the trailer of “Manufactured Landscapes” online.

What finally made me writing this article are some recent news about the Three Gorges Dam. First there was a video from National Geographic about landslides threating Chinese farmers. There they were still talking about a threat but today in the news there was already reported about a big landslide killing 34 people in the region of the Three Gorges.

Did you see the movie? Can we continue our extensive life forever? Can China handle this big challenge? Discuss it in the comments…

Check out musickum.com: Open Mind Index Generator, enter your last.fm buddy name and let you show how open-minded you are when it’s about listening to music. You can compare it with others from same country or with same music taste.

For example here my last.fm OMI:

As you can see is my index about 104. The mean index of the people using this tool was 94. The interesting thing is for example that the mean OMI for people mainly listening to music tagged “Hip-Hop” is only about 85! Wow, what’s wrong here? Did hip hop once grew up from many different directions of music and ideas for ending here? Or men are with a mean index of 94.76 more open minded than women with 92.90. How can we read this?

There are many other interesting things that you “could” interpret from these numbers. But already our maths professor said: “Don’t trust statistics when you didn’t fake it yourself”.

Now let’s give me your OMIs… Who is the most open minded here?

Another approach with the same result is the open source project QEMU. Its abstraction level is higher than with Xen and it can even emulate different target architectures from your current x86 host. So far x86_64, ARM, SPARC, PowerPC, MIPS and M68k target systems are supported. Its guest operating system does not need any single change to run on QEMU. This makes it very comfortable to test new live CDs or operating system images. But it is not so trivial to setup QEMU and Xen together on a Gentoo machine.

How to setup QEMU on 32bit Gentoo in Xen dom0?

If you compile Xen on a 32bit host you have to add ‘-mno-tls-direct-seg-refs’ to your CFLAGS. That is because the glibc TLS library is implemented in a way that will conflict with how Xen uses segment registers. For compiling the non-patched QEMU 0.9.0 you have to use a gcc version 3.x. The nowadays default gcc 4.x is not yet supported. After several compile failures I finally found to setup QEMU the following way:

1. For compiling gcc-3.x remove the ‘-mno-tls-direct-seg-refs’ from /etc/make.conf and set the ‘nossp’ and ‘nopie’ USE-flags. Otherwise gcc or later qemu will not compile.

2. Switch to gcc-3.x before compiling qemu-softmmu, qemu-user and qemu. In my case it’s: gcc-config i686-pc-linux-gnu-3.3.6

3. Check your CFLAGS again because the optimization flags for gcc 4.x are not always backwards compatible to gcc-3.x. In my case the make.conf looks like this:

# gcc-3.x
CFLAGS="-march=pentium4 -O2 -pipe -fomit-frame-pointer -mno-tls-direct-seg-refs"

# gcc-4.x for compiling gcc-3.3
#CFLAGS="-march=prescott -O2 -pipe -fomit-frame-pointer"

# gcc-4.x
#CFLAGS="-march=prescott -O2 -pipe -fomit-frame-pointer -mno-tls-direct-seg-refs"

4. Now you can compile QEMU. Do not forget to switch back to your original CFLAGS and gcc-4.x after successfully emerging QEMU. I recommend to you to also build the QEMU kernel accelerator module kqemu which has to be compiled with the same compiler as the kernel itself.

Now Xen and QEMU are able to run whatever operating system image you give them. Have fun with playing around…

Continuative links:

And once more I became weak because of a google thing. It’s the google webmasters tools. You can dig in a lot of google records of your Web site. Maybe more about this later…

Here a first nice “partner” site: