qemu – Grey Panthers Savannah https://grey-panther.net Just another WordPress site Mon, 21 Jul 2008 06:51:00 +0000 en-US hourly 1 https://wordpress.org/?v=6.9.4 206299117 Qemu codeswarm https://grey-panther.net/2008/07/qemu-codeswarm.html https://grey-panther.net/2008/07/qemu-codeswarm.html#respond Mon, 21 Jul 2008 06:51:00 +0000 https://grey-panther.net/?p=696 Codeswarm visualizations seem to be in-vogue now. So I put one together for the Qemu project. The music is from Jamendo (Paul D. Miller aka Dj Spooky). The video is licensed under the CreativeCommons Attribution-Noncommercial-Share Alike 3.0 license.

]]> https://grey-panther.net/2008/07/qemu-codeswarm.html/feed 0 696 Small Qemu tips https://grey-panther.net/2008/04/small-qemu-tips.html https://grey-panther.net/2008/04/small-qemu-tips.html#respond Sun, 13 Apr 2008 19:29:00 +0000 https://grey-panther.net/?p=777 It’s official: Ubuntu has the best documentation out there. There is almost no problem for it you can’t fix by typing "Ubuntu [description of the problem]" or "Ubuntu [error message]" in your favorite search engine.

For example, here you can find a very exhaustive documentation on installing Qemu and Kqemu (the Kqemu part is the really interesting one).

One interesting part it doesn’t explain is the "-localtime" switch (although it is correctly used in the examples). This switch tells Qemu to set the clock of the virtual machine to the local time rather than the UTC (also known as GMT) time. This is important because Windows and Linux have two different philosophies regarding the meaning of the BIOS (battery powered) clock: Linux thinks that it represents the UTC/GMT time and uses the specified time-zone to calculate the local time from it whenever needed, while Windows (and DOS) thinks that it should represent the local time and uses the time-zone to calculate the GMT time whenever needed (this is why dual-booting is problematic unless both OS’s use a network service to synchronize their time and/or you tweak Linux to set the BIOS clock to the local time). In conclusion: if you are running a Windows/DOS guest with Qemu from Linux, don’t forget to specify the "-localtime" switch.

And the last tip: Qemu recently moved from CVS to SVN. The new checkout command to obtain the source code is:

svn checkout http://svn.savannah.gnu.org/svn/qemu/

or if you are interested just in the trunk (not the branches and tags:

svn checkout http://svn.savannah.gnu.org/svn/qemu/trunk/

In case you don’t have Subversion installed (which is the case by default on Ubuntu) and you are running a Debian based system, it can be resolved with:

sudo apt-get install subversion

Update: changed sv to savannah to be correct (sv seems to deliver a 301 which svn doesn’t seem to handle)

]]> https://grey-panther.net/2008/04/small-qemu-tips.html/feed 0 777 Checking out CVS and creating patches https://grey-panther.net/2007/07/checking-out-cvs-and-creating-patches.html https://grey-panther.net/2007/07/checking-out-cvs-and-creating-patches.html#respond Thu, 05 Jul 2007 15:37:00 +0000 https://grey-panther.net/?p=849 Update: Qemu moved from CVS to SVN. While the CVS repository is (and will be) available for some time, you should look at the new checkout instructions.

Lately I started to dive into open-source development, specifically Qemu. Since I’m relatively new, here are some commands I found useful:

cvs -z3 -d:pserver:[email protected]:/sources/qemu co qemu – to check out the source code from a CVS repository, the Qemu source code in this case. Unfortunately CVS by default (without SSH tunneling, etc) uses a rather strange port (2401), which is firewalled at most places.

cvs diff -u vl.c vl.h > ../dump_traffic_to_pcap.patch – to create a so called patch (a list of differences between the files on your hard drive and the ones in CVS) file which can later be applied to the source code by the maintainer(s) of the project if s/he so chooses. This command must be issued from within the directory where the project was checked out, so that it can pick up the settings of the checkout.

Some tips I picked up until now (again, I’m by no means an expert):

  • Use the conventions of the source code. This means everything from commenting style, number of tabs to types of functions used (do they use fopen or open?).
  • Make your patches against the latest CVS version. It makes it easier for the maintainer(s) to apply your patch
  • Use Meld or WinMerge to port your patch to a new CVS version
  • Use dos2unix and unix2dos if you are doing cross-platform development (they can be found in the tofrodos package if you are using Ubuntu)
  • Be patient
]]> https://grey-panther.net/2007/07/checking-out-cvs-and-creating-patches.html/feed 0 849 What virtualization can and cannot do in an anti-malware context https://grey-panther.net/2006/12/what-virtualization-can-and-cannot-do-in-an-anti-malware-context.html https://grey-panther.net/2006/12/what-virtualization-can-and-cannot-do-in-an-anti-malware-context.html#respond Fri, 15 Dec 2006 07:46:00 +0000 https://grey-panther.net/?p=970 Over at the anti-virus rant blog (which is a nice blog because it includes the word rant in the title :)) Kurt Wismer states that virtualization is overhyped as a security technology. While I agree, I want to point out that following some simple rules, it can be a very powerful security which can easily replace a separate computer only for browsing. The rules would be:

  • Don’t have writable shares on the network the virtual machine is connected to. If you want to share a directory to extract file, share it from the client OS and copy it from outside
  • If possible put it on a different subnet
  • Use non-persistent hard disks or snapshots and revert to them regularly (currently the only commercial grade product that I know of that can do this is VMWare. QEmu also has this feature, but unfortunately it still needs some time to become a stable solution)

Following these rules you get a more secure and more convenient system than using a separate PC with something like DeepFreeze, but you loose the ability to stay logged on sites (because you loose all your cookies, history and cache).

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