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Almost Paravirtualized Introspection, But Not Quite

Published on Feb. 17, 2010 at midnight by XC

In the world of Virtualization, introspection refers to examining the memory of a running guest from the privileged domain at key addresses. For instance, if you know where to find the running kernel task structure, you can read it while the guest is completely oblivious that you are doing so. In other words, it allows you to observe a running application without interfering with it at all. In an ideal world, this would be an easy process. Unfortunately, its not.

The Xen Introspection Project has made amazing strides in their attempt to simplify the process. Unfortunately, this means keeping a list of kernels and interesting addresses up to date for every possible operating system. That’s quite a chore, needle in a haystack mean anything to you?
One of the reasons that I love running mostly paravirtualized domains is the benefit of Xenbus, a communication channel between the privileged and guest domains. Using this, ‘split’ drivers can easily communicate with their backing counterparts on the privileged side, and vice versa. My goal a few months ago was to find a way to monitor the health and status of a large paravirtualized farm without relying on something like SNMP. In fact, some of the guests don’t have networking, all they do is crunch data on a clustered file system.

I first looked at real introspection, but this led me to several insurmountable obstacles.

Category: Free Software
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Breaking Out Of Posix Thinking

Published on Feb. 17, 2010 at midnight by XC

I have realized that I am spoiled by the same standards that I was so happy to see succeed. I hate to admit it, but I now get uncomfortable in the absence of glibc or dietlibc. I get even more uncomfortable in the absence of POSIX signals and NPTL. I then think back to days where all I wanted was a good compiler and something that gave me most of C89. I don’t know if this is a bad progression, after all, its good to get used to widely used standards. It sure does hinder your sense of adventure though.

I’m in the middle of updating bdsh, the simple command line interface (that looks like a shell) I wrote for HelenOS. There’s some new bits in libc that need a convenient testing facility, additionally its now possible for tasks to inherit the parent console which means redirection will need to happen sooner than later.

Of all the things I work on, I enjoy hacking away at HelenOS the most. Its the most challenging, taking on and learning an entirely new approach to IPC, getting used to a micro kernel (again, this ain’t your daddy’s Minix!) while watching stuff like networking still take shape. Its the start of a truly modern operating system. And yet, I find myself leaning to and suggesting POSIX like behavior. If nobody thought out of the box, we wouldn’t get very far
Just because it resembles UNIX a little does not mean you are breaking the law by throwing POSIX out the window.

Category: Free Software
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Raw Therapee Becomes Free Software

Published on Jan. 20, 2010 at midnight by XC

In case you have not heard (this was covered on Slashdot and I’m sure the rest), Raw Therapee is now available under the terms of the GNU General Public License (Version 3 or later). Other than wishing it was GPL V2 or later, I’m really excited about this.

Even though I have the option, I usually don’t shoot in RAW for two reasons:

Ubuntu is my primary OS (after all, I love taking pictures, but programming pays the bills), RAW conversion is a pain there.
The only Windows PC I have is my netbook, hardly suitable for selecting, much less correcting or converting.
I know I said two reasons, oh well. I don’t edit most of my stuff, if its THAT bad, I learn what I can from it and try to shoot it again. Having RAW output accessible might discourage what has proven to be a really good habit. I treat DSLRs like film cameras, mostly, beyond the few minor corrections (or perhaps de-saturation) that I use.

Some really good things are going to come out of this. The original author will be able to spend his time doing what he really likes doing, working on the algorithms that make converting and correcting easier, while people who enjoy UI design can work on making the program friendlier and more intuitive. Since a large number of programmers are also amateur (or better) photographers, I have a feeling forks of this are going to start flying around like lightning.

Category: Free Software
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And The Package Manager Debate Rages On

Published on Aug. 8, 2009 at midnight by XC

If you ask any *NIX engineer what they love or hate the most about their operating system of choice, many will indicate the package manager. For those of you who don’t use a UNIX like operating system, the package manager is the program that lets you install other programs.

A small group of developers (me inclued) have been hasing out the blue prints for a new kind of server operating system on IRC the past few weeks. Since the package manager is crucial for every phase in the life cycle of an operating system (from installation, to updates all the way to upgrading to the latest release) … it tends to get the most attention in our discussions.
A lot of my co-developers think that I am anti-RPM, this is not the case. I like RPM, I just think that yum is slow and brain dead. My natural solution was going to something like apt-rpm, to get the power of apt’s dependency resolution and speed while enjoying the convenience and simplicity of building RPMs. Many of you may note, it is very easy to upgrade from a previous Ubuntu long term support distribution to the latest long term support distribution, with zero dependency conflicts.

I can not help but consider how our target audience (developers and system integrators) are going to use our software.

Category: Free Software
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Cisco Settles With The Free Software Foundation

Published on May 21, 2009 at midnight by XC

Brett Smith, licensing engineer for the FSF writes:

BOSTON, Massachusetts, USA -- Wednesday, May 20, 2009 -- The Free Software Foundation (FSF) and Cisco Systems, Inc. are pleased to announce that they have reached a joint agreement.
Under the agreement, the FSF has agreed to dismiss its lawsuit against Cisco.

Cisco has agreed to appoint a Free Software Director for Linksys, a subsidiary of Cisco, to supervise Linksys' compliance with the requirements of free software licenses such as the GPL (the GNU General Public License). The Free Software Director will report periodically to the FSF regarding Linksys' compliance efforts. Cisco has further agreed to take certain steps to notify previous recipients
of Linksys products containing FSF programs of their rights under the GPL and other applicable licenses, to publish a licensing notice on the Linksys website, and to provide additional notices in a separate publication. In addition, Cisco will continue to make the complete and
corresponding source code for versions of FSF programs used with current Linksys products freely available on its website. Cisco will also make a monetary contribution to the FSF.
The parties recognize Cisco's ongoing obligations under the GPL and other free software licenses. The FSF will continue to independently monitor Linksys' compliance with these licenses, and work with Linksys to resolve any new issues that may arise.
"We are glad that Cisco has affirmed its commitment to the free software community by implementing additional measures within its compliance program and dedicating appropriate resources to them, further reassuring the users' freedoms under the GPL," said Peter Brown, Executive Director of the FSF. "Our agreement results in making all of the relevant source code available in the fastest way possible."
### About the FSF
The Free Software Foundation, founded in 1985, is dedicated to promoting computer users' right to use, study, copy, modify, and redistribute computer programs. The FSF promotes the development and use of free (as in freedom) software -- particularly the GNU operating system and its GNU/Linux variants -- and free documentation for free software. The FSF also helps to spread awareness of the ethical and political issues of freedom in the use of software, and its Web sites, located at fsf.org and gnu.org, are an important source of information about GNU/Linux. Donations to support the FSF's work can be made at <http://donate.fsf.org>. Its headquarters are in Boston, MA, USA.
### Media Contacts
Brett Smith
Licensing Compliance Engineer
Free Software Foundation
+1 (617) 542 5942 x18

The FSF fell under some criticism after filing this law suit, many critics cited that the suit would alienate a very big ally (Cisco). What many people fail to remember is that the FSF is the custodian of not only the GPL, but also the copyright of thousands of people who released programs under the GPL.

A failure to act, after years of complaints would have not only diminished the worth and purpose of the FSF in the eyes of its community, it would have potentially alienated key developers within that community.

As I noted before, this is the first time (ever) that the FSF has had to assert its license and copyright in the form of a suit .. thankfully, it was settled out of court.

Note – Cisco inherited this headache when they purchased Linksys. Prevention in matters such as software licensing is always better than a cure.

The FSF’s press release can be found here.

Category: Free Software

Cisco Sued By The Free Software Foundation

Published on Dec. 15, 2008 at midnight by XC

I don’t think that anyone ever dreamed of the Free Software Foundation needing to enforce its license and copyright in a court of law, however, this unlikely event has happened. The FSF is suing Cisco Systems for violating version 2 of the GNU General Public License and Lesser GPL. You can read the complaint here in relatively plain English minus legalese. If you are a programmer that works with software governed by the GPL, I strongly suggest that you read the complaint.

The FSF filed suit in hopes of bringing an end to a five year game of `whack a mole‘, as FSF license compliance engineer Brett Smith writes:

As we always do in violation cases, we began a process of working with Cisco to help them understand their obligations under our licenses, and how they could come into compliance. Early on it seemed likely that we could resolve the issues without any fuss.

While we were working on that case, though, new reports came in. Other Cisco products were not in full compliance either. We started talking to the company about those as well—and that’s how a five-years-running game of Whack-a-Mole began. New issues were regularly discovered before we could finish addressing the old ones.

The lawsuit could prevent Cisco/Linksys products that are assembled in China from being imported to the US until the FSF is satisfied with Cisco’s diligence in complying with the GPL2, pending damages that could range in the millions.

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Xguests 1.0.8 Released

Published on Oct. 14, 2008 at midnight by XC

Xguests, a program to print interesting information about guests running under the Xen (TM) hypervisor has reached version 1.0.8.

Xguests does not require xend to be running and will print information in the following formats:

XML 1.0
PHP Array
Perl Array
BASH Array
Easy to scrape text
‘xm list’ style

Below is the message sent to xguests-general:

I'm pleased to announce the release of Xguests version 1.0.8! This
release includes some new functionality, several bug fixes,
documentation and other juicy goodies for your dom-0 host.
Most notably, daemonization is now proper, guest status is conveyed in
all outputs, output resembling 'xm list' is now available and the tree
is much cleaner. You could use xguests in your own programs, if you
Downloads are available (source .tgz) at:
Or just update your Mercurial repository against:
Contributions are below:
Version 1.0.8:
Tim Post <echo@echoreply.us> (8)
* Fix xguests_find_state() to reuse the same pointer
* Add IPC handlers for child when in -d/--daemon mode
* Add guest status output to all displays
* ctyle / formatting fixes
* Ensure the return value of malloc() is always cast to avoid
breaking c++ compilers
* Finish common Makefile targets
* cstyle (80 column limit on most functions, ensure return value
of malloc() is cast)
Corey Henderson <corman@cormander.com> (6)
* Fix issue in XML output format
* Add 'list' format similar to xm list
* Add function to return status of guests to xg mini lib
* Enforce ARG_MAX on -f option
* Allow stdout to be a valid descriptor for -f, eliminate dups
* Auto output type based on file extension
As I said previously, 1.0.9 is reserved as a bugfix version should
anything horribly wrong be found in this release. If all goes well,
we're jumping to 1.1.0 which will entail:
* Eliminating libxenstat in favor of libxenctrl
* Basic 'xm' functionality that does not rely on Xend, such as
'create', 'shutdown', 'pause', 'destroy', 'reboot', 'save',
'restore' and more. 'list' will of course keep all available
output formats.
* More perks if we get the above completed correctly in less
time than anticipated.
* Simplified ./configure && make && make install installation,
also allowing for packagers to include xguests
Use in good health!

So, enjoy

Category: Free Software

Jakub Jermar On Helenos

Published on Aug. 20, 2008 at midnight by XC

Recently, I had the opportunity to interview Jakub Jermar via e-mail regarding his motivation behind creating and advancing HelenOS, an operating system based on the from-scratch Spartan microkernel. An important disclaimer, I am a contributor to HelenOS for my own reasons. My status as a contributor did not stop me from challenging Jakub with interesting questions.

Microkernels are most decidedly not dead, the amount of people working on things like Minix, L4 and (yes, even to this date) Mach represent a considerable interest in an “old but new” kernel design.

Who is Jakub, what is HelenOS, why make HelenOS?
This is not a resurrection of the Torvalds/Tanenbaum debate although that debate was quite funny if you remember it. We’ve grown past most of those arguments. In the future, I’ll challenge Jakub and others to another interview and really get in to the nuts and bolts. For now, enjoy.

Who is Jakub, where do you work, what do you do?
I am a 27 year old Czech who enjoys system programming. At the moment, I work for Sun Microsystems. I fix bugs in Solaris kernels and the related low-level libraries. Besides operating systems, I also like compilers, but unfortunately I don't have much free time for doing serious compiler work. I am married but still have no children. When I am not spending the rest of my free time with my wife, I can be found working on HelenOS.

Category: Free Software
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Time For More Tutorials

Published on June 6, 2008 at midnight by XC

I’m (nearly) done converting all of my existing documentation into Asciidoc format. Its time to write more tutorials. What remains is, what to write?

I could do more Xen centric stuff, perhaps some bits on how to setup storage servers, roll your own single system image cluster? I’d rather write what people actually need.

So, what do you need to learn how to do? Comments are open.

Category: Free Software

Srce Interim Security Release 1.0.8

Published on May 6, 2008 at midnight by XC
Category: Free Software