With the last git release, git-rebase gained a new option: --interactive. If you already had the feeling that in a patch series of yours you should have ordered patches differently, or merged some, then this command is what you dreamed of. Here is how it works Let's pretend you want to rework your last 10 patches, you'll run:

   $ git rebase -i HEAD~10

It will launch your $EDITOR and you'll see something like:

   # Rebasing 16d3800..14f3d11 onto 16d3800 
   # 
   # Commands: 
   #  pick = use commit 
   #  edit = use commit, but stop for amending 
   #  squash = use commit, but meld into previous commit 
   # 
   # If you remove a line here THAT COMMIT WILL BE LOST. 
   # 
   pick 6270640 Simplify write_tree using strbuf's. 
   pick 27c528a Further strbuf re-engineering. 
   pick fd82c9a Eradicate yet-another-buffer implementation in buitin-rerere.c 
   pick eee488f More strbuf uses in cache-tree.c. 
   pick 16878b5 Add strbuf_rtrim and strbuf_insert. 
   pick e9081af Change semantics of interpolate to work like snprintf. 
   pick 99c3ef5 Rework pretty_print_commit to use strbufs instead of custom buffers. 
   pick 203db5d Use strbuf_read in builtin-fetch-tool.c. 
   pick a20d939 Use strbufs to in read_message (imap-send.c), custom buffer--. 
   pick 14f3d11 Replace all read_fd use with strbuf_read, and get rid of it.
   ~
   ~
   ~
   ~
   ~
   ~[]

Then you can rewrite "pick" into "edit" if you want to change something in a commit, or "squash" if you want to merge it with the one from the line before. What the small help doesn't say is that you can actually reorder your commits, and it will do what you expect it to do. I used it 10 minutes ago, because I have this string buffer module I extend on a regular basis, I squashed every API extension of that module in one commit using that. Each time one change needs you to edit anything because either you asked for it, or that one of the change you asked for generated a conflict, then as usual the rebase will stop. You will be prompted to make the change, or fix the conflict, or merge comments (in case of a squash), and when all is in order, you just need to:

   $ git rebase --continue

This is just awsomely simple and intuitive

After dealing with Optus phone support [1] in regard to a routine request for a password change I have been thinking about better ways of managing password changes for a large ISP. The first criteria is that the user must have a password that is difficult to brute-force attack at all times. Changing a password to a supposedly temporary value that can be easily guessed (such as “changeme“) is never acceptable. The next criteria is that the help-desk operator should be trusted as little as possible and it would be ideal if they never knew the password. One possibility that occurred to me is that each bill could have a six-digit pseudo-random number printed on it. This number could be used as an alternate password. When a customer calls up because they lost their password they almost always have their last bill (this is why they print the number for phone support on each bill). The help-desk operator could then push a button on a web based form that makes this pseudo-random number be their new password, thus the help-desk operator would not know the new password and the user would also have it printed out clearly which avoids the confusion from having a password read out in a foreign accent. Another possibility is to have the password change infrastructure integrated with the CTI [2] system, then the help-desk operator could push a button and have the computer dictate the password without the help-desk operator being able to listen in. There will always be corner cases where a help-desk operator has to change the password, but if these are rare because the automated system handles most cases then the potential for damage would be limited. Of course it would also be a really good idea to do some statistical tracking of the number of password change requests performed by each operator and investigate those who do significantly more than average. In the past AOL has experienced a variety of security problems related to trojans [3] which probably would have been discovered by such analysis. Another possible option is that customers with mobile phones could have their new password sent to them by SMS. It’s quick, easy, cheap when done in bulk, and is much harder to intercept than most methods that might be used for transferring passwords. References:

1. http://etbe.coker.com.au/2007/09/03/optus-password-changeme/


2. http://en.wikipedia.org/wiki/Computer_telephony_integration


3. http://www.wired.com/techbiz/it/news/2003/02/57753

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So, for some reason, I was using advogato and, for some reason, I was looking at jono and, for some reason, I clicked on the link to the JonoCam. What I saw was unpleasant and not what I was expecting. Someone's squatting on the JonoCam address, hiding behind eNom's privacy service. In fact, it looks like all of kdedevelopers.net is spam now, including jono.kdedevelopers.net. Not only that, but http://www.jonobacon.co.uk/ is squatted too, by futuregate aka Mindcom Internet Limited of 20 Meridian Way, Meridian Business Park, Norwich NR7 0TA. If you're reading this from near Norwich, would you post some pictures of the home of these serial domain-squatters, please? So I hopped onto the lugradio IRC and asked jono. Apparently he lost it ages ago(!) nominet says the domain was registered in 2004 and last updated April 2007, so I didn't know if that means it's been a while, or just a few months. Does the registration date change if an owner loses control? astinus told me that it does. Anyway, I wonder how many advogato users have disused person pages with spam/squatted links. Is there a nice way we could spot them all and tag them somehow? Is there some common "about me" format which advogato (and social networking sites?) could use to keep up-to-date on our movements? List three locations in case we lose our primary domain? Also, I had another email yesterday from someone apologising for losing control of their domain, asking me to change my links and I've removed a couple more from my friends bookmarks category recently. Are people still losing personal domains to squatters? If so, is there a new reason for this, or is it the same old problems of registrar-lock-in and it being cheaper to register a new domain than to go to dispute resolution? (2007-09-09: 4 comments)

I just released new version of Gammu. Besides experimental support for Bluetooth on FreeBSD, this release is mostly about fixing found bugs. Full list of changes:

• Fixed parsing of date/time reply from some broken AT phones.
• Added support for Option GlobeTrotter.
• Handle correctly when phone automatically saves message to different memory than we ask.
• Fixed buffer overflows, thanks to Gentoo folks for noticing.
• Detect when phone is waiting for phone code.
• Added experimental support for Bluetooth on FreeBSD.
• SMSD can execute programs on message receiving (thanks to zaf).
• Allow to define Bluetooth channel in configuration.

I do not plan to introduce any new major features to upcoming stable 1.14.0, this should be only about stabilization - there are some regressions from past in SMS decoder on Windows, which should be really fixed, there are also some other bugs reported on SMS decoder, so I should probably finally get to this part of code, understand it and do what is needed to make it more mature.

Hello World I have finally a new Hackergotchi, I can’t do that myself since I’m quite unable to do any graphics work. So my coworker Markus Roth helped me, thank you! I will upload it to the SVN and modify the configfile according as soon as the CVS->SVN migration for planet.debian.org is over. Thanks and Regards,

A fairly common request is to be able to duplicate a Xen instance. For example you might have a DomU for the purpose of running Wordpress and want another DomU to run MediaWiki. The difference in configuration between two DomU’s for running web based services that are written in PHP and talking to a MySQL back-end is quite small, so copying the configuration is easier than a clean install. It is a commonly held opinion that a clean install should be done every time and that Kickstart on Red Hat, FAI on Debian and comparable technologies on other distributions can be used for a quick automatic install. I have not yet got FAI working correctly or got Kickstart working on Xen (it’s on my todo list - I’ll blog about it when it’s done). Regardless of whether it’s a good idea to copy a Xen DomU, there are often situations where clients demand it or when it’s impractically difficult to do a fresh install. I believe that the most sensible way to store block devices with Xen is to use LVM. It is a requirement for a Xen system that you can easily create new block devices while the machine is running and that the size of block devices can be changed with minimal effort. This rules out using Linux partitions and makes it unreasonably difficult to use LUNs on a fiber-channel SAN or partitions on a hardware RAID. LVM allows creating new block devices and changing the size of block devices with minimal effort. Another option would be to use files on a regular filesystem to store the filesystem data for Xen DomU’s, if choosing this option I recommend using XFS [1] filesystem (which delivers good performance with large filesystems and large files). If you use XFS to store the block devices for the DomU that you want to copy then you will need to halt the DomU for the duration of the copy as there is no other way of getting an atomic copy of the filesystem while it’s in use. The way of doing this would be to run the command “xm console foo ; cp /mnt/whatever/foo-root /mnt/whatever/bar-root ; xm create -c foo” where “foo” is the name of the DomU and “/mnt/whatever/foo-root” is the file that is used to store the root device for the DomU (note that multiple cp commands would be needed if there are multiple block devices). The reason for having the two xm commands on the one line is that you initially login to the DomU from the console and type halt and then the xm command will terminate when the DomU is destroyed. This means that there is no delay from the time the domain is destroyed to the time that the copy starts. If you use LVM to store the block device then things are a little easier (and you get no down-time). You simply run the command “lvcreate -s -L 300m -n foo-snap /dev/V0/foo-root” to create a snapshot with the device name /dev/V0/foo-snap which contains a snapshot the of the LV (Logical Volume) /dev/V0/foo-root. The “-L 300m” option means to use 300Meg of storage space for the snapshot - if the writes to /dev/V0/foo-root exceed 300Meg of data then your snapshot breaks. There is no harm in setting the allocated space for the snapshot to be the same as the size of the volume that you are going to copy - it merely means that more disk space is reserved and unavailable for other LVM operations. Note that V0 needs to be replaced by the name of the LVM VG (Volume Group) Once you have created the snapshot you can create a new LV with the command “lvcreate -n new-root -L X /dev/V0” where X is the size of the device (must be at least as big as the device you are copying) and then copy the data across with a command similar to “dd if=/dev/V0/foo-snap of=/dev/V0/new-root bs=1024k“. After the copy is finished you must remove the snapshot with the command “lvremove /dev/V0/foo-snap” (please be very careful when running this command - you really don’t want to remove an LV that has important data). Note that in normal operation lvremove will always give a prompt “Do you really want to remove active logical volume“. If you made the new device bigger then you must perform the operations that are appropriate for your filesystem to extend it’s size to use the new space. There is no need to copy a swap device, it’s easier to just create a new device and run mkswap on it. After copying the data you will need to create the new Xen config (by copying /etc/xen/foo to the new name). Make sure that you edit the Xen config file to use the correct block devices and if you are specifying the MAC address [2] by a “vif” line in the config file make sure that you change them to unique addresses for your LAN segment (reference [2] has information on how to select addresses). Now you must mount the filesystem temporarily to change the IP address (you really don’t want two DomU’s with the same IP address). If your Dom0 has untrusted users or services that are accessed by untrusted users (IE any Internet facing service) then you want to mount the filesystem in question with the options nosuid and nodev so that if the DomU has been cracked it won’t allow cracking of the Dom0. After changing the configuration files to change the IP address(es) of the DomU you can then umount the filesystem and start it with the xm create command. If instead of creating the clone DomU on the same Dom0 you want to put it on a different system you can copy the block devices to files on a regular filesystem on removable media (EG an IDE disk with USB attachment). When copying the block devices you also need to copy the Xen configuration and edit it to reflect the new paths to block devices for the data once it’s copied to the new server, but you won’t necessarily need to change the MAC address if you are copying it to a different LAN segment. References:

1. http://en.wikipedia.org/wiki/XFS


2. http://en.wikipedia.org/wiki/MAC_address

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Hello World While reading planet.ubuntu.com I notified especially the post from Christer Edwards, “Call for Ubuntu stats”. Especially the following two questions seem very interesting to me:

• Estimated number of users
• Estimated number of countries deployed

Does anyone have an idea? I don’t see a way how we can calculate that, the mirrors are decentral, Debian doesn’t force it’s user to register somewhere. Nevertheless, some numbers (no matter if really precise) would be very interesting. Please send comments or get in contact with me by E-Mail. Thanks and regards,

A significant problem with the old-fashioned media is that as a general rule they don’t cite references for anything. Some of the better TV documentaries and non-fiction books cite references, but this is the exception not the norm. Often documentaries only cite references in DVD extras which are good for the people who like the documentary enough to buy it but not for people who want to rebut it (few people will pay for a resource if they doubt the truth and accuracy of it’s claims). I can understand newspapers not wanting to publish much in the way of background information in the paper version as every extra line of text in an article is a line of advertising that they can’t sell. So they have financial pressure to produce less content, and the number of people like me who want to check the facts and figures used in articles is probably a small portion of the readership. Another issue with newspapers is that they are often considered as primary authoritative sources (by themselves and by the readers). It is often the case that journalists will interview people who have first-hand knowledge of an issue and the resulting article will be authoritative and a primary source in which case all they need to do is to note that they interviewed the subject. However the majority of articles published will be sourced from elsewhere (news agencies [ http://en.wikipedia.org/wiki/News_agency ] such as Reuters are commonly used). Also articles will often be written based on press releases - it is very interesting to read press releases and see how little work is done by some media outlets to convert them to articles, through a well written press release a corporation or interest group can almost write it’s own articles for publication in the old media. One way of partially addressing the problem of citing references in old media would be to create a web site of references, then every article could have a URL that is a permanent link to the references and calculations to support the claims and numbers used. Such a URL could be produced by any blogging software, and a blog would be an ideal way of doing this. For bloggers however it’s much easier to cite references and readers have much higher expectations of links to other sites to support claims and of mathematical calculations shown to indicate how numbers are determined. But there is still room for improvement. Here are some of the most common mistakes that I see in posts by people who are trying to do the right thing:

1. Indirect links. When you refer to a site you want to refer to it directly. In email (which is generally considered a transient medium) a service such as TinyURL [ www.TinyURL.com ] can be used to create short URLs to refer to pages that have long URLs. This is really good for email as there are occasions when people will want to write the address down and type it in to another computer. For blogging you should assume that your reader has access to browse the web (which is the case most of the time). Another possibility is to have the textual description of a link include a reference to the TinyURL service but to have the HREF refer to the real address. Any service on the net may potentially go away at some future time. Any service on the net may have transient outages, and any reader of your blog may have routing problems that make parts of the net unavailable to them. If accessing a reference requires using TinyURL (or a similar service) as well as the target site then there are two potential things that might break and prevent your readers from accessing it.
   One situation where indirect links are acceptable is for the printed version. So you could have a link in the HTML code for readers to click on to get to the reference page directly and a TinuURL link for people who have a printed version and need to type it in.
   Also when linking to a blog it’s worth considering the fact that a track-back won’t work via TinyURL and track-backs may help you get more readers…


2. Links that expire. For example never say “there’s a good article on the front page of X” (where X is a blog or news site). Instead say “here’s a link to a good article which happens to be on the front page now” so that someone who reads your post in a couple of years time can see the article that you reference.
   Another problem is links to transient data. For example if you want to comment on the features of a 2007 model car you should try to avoid linking to the car manufacturer page, next year they will release a new car and delete the old data from their site.
   A potential problem related to this is the Google cache pages which translate PDF to HTML and high-light relevant terms and can make it much easier to extract certain information from web pages. It can provide value to readers to use such links but AFAIK there is no guarantee that they will remain forever. I suggest that if you use them you should also provide the authoritative link so that if the Google link breaks at some future time then the reader will still be able to access the data.


3. Not giving the URLs of links in human readable form. Print-outs of blog pages will lose links and blog reading by email will also generally lose links (although it would be possible to preserve them). This counts for a small part of your readership but there’s no reason not to support their needs by also including links as text (either in the body or at the end of the post). I suggest including the URL in brackets, the most important thing is that no non-URL text touch the ends of the URL (don’t have it in quotes and have the brackets spaced from it). Email clients can generally launch a web browser if the URL is clear. Note that prior to writing this post I have done badly in this regard, while thinking about the best advice for others I realised that my own blogging needed some improvement.
   I am not certain that the practice I am testing in this post of citing URLs inline will work. Let me know what you think via comments, I may change to numbering the citations and providing a list of links in the footer.


4. Non-specific links. For example saying “Russell Coker wrote a good post about the SE Linux” and referring to my main blog URL is not very helpful to your readers as I have written many posts on that topic and plan to write many more (and there is a chance that some of my future posts on that topic may not meet your criteria of being “good”). Saying “here is a link to a good post by Russell Coker, his main blog URL is here” is more useful, it gives both the specific link (indicating which post you were referring to) and the general information (for people who aren’t able to find it themselves, for the case of deleted/renamed posts, and for Google). The ideal form would be “<A HREF=”http://etbe.coker.com.au/whatever”>here is a link to a good post by Russell Coker [ http://etbe.coker.com.au/whatever ]</A>, his main blog URL is <A HREF=”http://etbe.coker.com.au/”> [ http://etbe.coker.com.au ]</A>” (note that this is an example of HTML code as a guide for people who are writing their own HTML, people who use so-called WYSIWYG editors will need to do something different).


5. Links that are likely to expire. As a rule of thumb if a link is not human readable then the chance of it remaining long-term is low. Companies with content management systems are notorious for breaking links.


6. Referencing data that you can’t find. If you use data sourced from a web site and the site owner takes it down then you may be left with no evidence to support your assertions. If data is likely to be removed then you should keep a private copy off-line (online might be an infringement of copyright) for future reference. It won’t let you publish the original data but will at least let you discuss it with readers.


7. Referencing non-public data. The Open Access movement [ http://en.wikipedia.org/wiki/Open_access ] aims to make scholarly material free for unrestricted access. If you cite papers that are not open access then you deny your readers the ability to verify your claims and also encourage the companies that deny access to research papers.
   An insidious problem is with web sites such as the New York Times [ www.nytimes.com ] which need a login and store cookies. As I have logged in to their site at some time in the past I get immediate access to all their articles. But if I reference them in a blog post many readers will be forced to register (some readers will object to this). With the NYT this isn’t such a problem as it’s free to register so anyone who is really interested can do so (with a fake name if they wish). But I still have to keep thinking about the readers for such sites.
   I should probably preview my blog posts from a different account without such cookies.


8. Failing to provide calculations. My current procedure is to include the maths in my post, for example if you have a 32bit data type used to store a number of milliseconds then it can store 2^32/1000 seconds which is 2^32/1000/60/60/24 = 49.7 days, in this example you can determine with little guessing what each of the numbers represent. For more complex calculations an appendix could be used. A common feature of blogs is the ability to have a partial post sent to the RSS feed and the user has the ability to determine where the post gets cut. So you could cut the post before the calculations, the people who want to see them will find it’s only one click away, and the people who are happy to trust you will have a shorter post.


9. Linking with little reason. Having a random word appear highlighted with an underline in a blog post is often not very helpful for a reader. It sometimes works for Wikipedia links where you expect that most readers will know what the word means but you want to link to a reference for the few who don’t (my link for the word Wikipedia is an example). In the case where most readers are expected to know what you are referring to then citing the link fully (with a description of the link and a human-readable form for an email client) is overkill and reduces the readability of the text.
   The blogging style of “see here and here for examples” does not work via email and does not explain why a reader should visit the sites. If you want to include random links in a post then having a section at the footer of related links would probably be best.


10. Linking to a URL as received. Many bloggers paste URLs from Google, email, and RSS feeds into their blog posts. This is a bad idea because it might miss redirection to a different site. If a Google search or an email gives you a URL that is about to go away then it might redirect to a different site. In that case citing the new URL instead of the old one is a service to your readers and will decrease the number of dead-links in your blog over the long-term. Also using services such as www.feedburner.com may cause redirects that you want to avoid when citing a blog post, see my previous post about Feedburner [ http://etbe.coker.com.au/2007/08/20/feedburner-item-link-clicks/ ].

Here are some less common problems in citing posts:

1. Inappropriately citing yourself. Obviously if there is a topic that you frequently blog about then there will be benefit to linking to old posts instead of covering all the background material, and as long as you don’t go overboard there should not be any problems (links to your own blog are assumed to have the same author so there is no need for a disclaimer). If you write authoritative content on a topic that is published elsewhere then you will probably want to blog about it (and your readers will be interested). But you must mention your involvement to avoid giving the impression that you are trying to mislead anyone. This is particularly important if you are part of a group that prepares a document, your name may not end up on the list of authors but you have a duty to your readers to declare this.
   Any document that you helped prepare can not be used by itself as a support of claims that you make in a blog post. You can certainly say “I have previously demonstrated how to solve this problem, see the following reference”. But links with comments such as “here is an example of why X is true” are generally interpreted to be partly to demonstrate the popular support for an idea.


2. Citing secret data. The argument “if you knew what I know then you would agree with me” usually won’t be accepted well. There are of course various levels of secrecy that are appropriate. For example offering career advice without providing details of how much money you have earned (evidence of one aspect of career success) is acceptable as the readers understand the desire for some degree of financial secrecy (and of course in any game a coach doesn’t need to be a good player). Arguing the case for a war based on secret data (as many bloggers did) is not acceptable (IMHO), neither is arguing the case for the use of a technology without explaining the science or maths behind it.


3. Not reading the context of a source. For example I was reading the blog of a well regarded expert in an area of computer science, and he linked to another blog to support one of his claims. I read the blog in question (more than just the post he cited) and found some content that could be considered to be racially offensive and much of the material that I read contained claims that were not adequately supported by facts or logic. I find it difficult to believe that the expert in question (for whom I have a great deal of respect) even casually inspected the site in question. In future I will pay less attention to his posts because of this. I expect a blogger to pay more attention to the quality of their links than I do as a reader of their blog.

While writing this post I realised that my own blogging can be improved in this regard. Many of my older posts don’t adequately cite references. If you believe that any of my future posts fail in this regard then please let me know.

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The short story: we lost the baby. "Cord accident". The long story: Sarah woke me up at about 2:30am on Tuesday morning in a panic because she'd woken up herself at about 2am, and realised that she hadn't felt the baby move since about 8am the previous day. I had a quick feel, but couldn't feel anything like his usual vigorous kicking, and eager to put her mind at rest, called Labor an Delivery at Lucile Packard Children's Hospital to see if we could come in. They said we could, so we jumped in the car and got there at about 3:25am. They hooked up Sarah to a fetal heart monitor, but after anxious minutes, they couldn't pick up anything, so they got out the ultrasound machine. It was pretty obvious from that that there was no movement. We'd lost him. So from about 4am onwards, we, well, tried to come to grips with the fact that we'd lost our baby. That we'd been robbed, 13 days from the finish line, and that we weren't going to be bringing a baby home to all the stuff we had ready for him there. The doctors briefly mulled over whether to have a C-section to deliver Joshua, as was the plan, or induce. Apparently it's psychologically better for the mother if she delivers naturally, since she doesn't have the constant reminder for 6+ weeks while she recovers from the C-section. However, the doctors decided that as nothing had really changed from a delivery point of view, and they wanted to do a C-section for reduced strain on Sarah's heart, they opted for a C-section. They managed to get a free operating room slot in the Stanford ORs, so they transferred Sarah over there, and they started performing the surgery at about 10am. Joshua was delivered sometime around 10:15am. I got to see him and hold him while we were still in the OR. He was perfect. 4 pounds 12 ounces. He didn't look that small. We were wondering if he was going to make 5 pounds or not. Maybe he would have by the 17th. I brought him around to show Sarah while she was still on the table, but it was hard to get him up to a good position that she could see him from, and she was a bit zonked out from all of the drugs. They finished up at about 10:45am, and took her to the recovery room, where they didn't really want me, so one of the nurses from Labor and Delivery took me back to Lucile Packard, to spend some time with Joshua. There she let me hold him for a while, and look at him, and take some photographs. Then she weighed him and measured him, and took some more photographs. The nurse was really compassionate about the whole thing, and it felt like we were there for a good couple of hours, which was good, because apparently Lucile Packard and Stanford don't really inter-operate very well, and whilst physically transferring a patient just involves wheeling them down a corridor, getting all the paperwork sorted out is a completely different story. So while Sarah was only supposed to spend an hour in recovery, she spent three hours there, because they were waiting on paperwork to release her, then waiting on a room to be available, then the right people weren't talking to each other, so they didn't know they didn't know that a room was available from midday. I forget what time we actually got out of recovery. The doctors, being the overcautious bunch of people that they are, wanted to keep Sarah in the Cardiac Surveillance Unit for 24-48 hours so they could check on her vitals post-delivery. They let us out of there late today. We're currently in a general ward. I thought they said it was for gynaecology patients (they didn't think it'd be terribly considerate to stick us in with all the other recovering mothers and their babies), but there's some male patients in here too, so I'm not sure what this ward is. In terms of coming to grips with things, they brought Joshua up to our room for pretty much as long as we wanted yesterday, and Sarah was more with it by then, so she could hold him, and we could take more photographs. It's been really hard. I was awake from when Sarah woke me up in the morning until about 10pm that night. Fortunately I was able to get a cot in the room with Sarah, so I could stay the night there. I'm staying here tonight as well. The obstetrician that delivered Joshua said that his umbilical cord was wrapped around his neck twice and once around his body, and was pretty tight around his neck. They can't say for sure that that's what happened, but it's a good enough explanation for us, and we're not going to have the little guy cut up for an autopsy, which may not tell us anything anyway. So we're taking some small comfort from the fact that we're able to make a healthy looking baby, and that Sarah's heart performed fine throughout the pregnancy and delivery, and that this was just one of those so very unlucky accidents. Apparently babies get their umbilical cords wrapped around their necks all the time, and most of the time it's not a problem. So we know that he didn't have any birth defects, and it wasn't because of something Sarah ate, or because Sarah got sick or anything. It's just plain bad, rotten luck. We'll most probably try again, but the next pregnancy is going to be hell. It'll be like walking on egg shells the entire time. Clearly, your baby isn't out of the water until he's screaming in the delivery room. There's a lot more I want to write, but I also want to get this finished and get some sleep, so here's a brain dump of what's been going through my head for the last 48 hours:

• Dammit!
• Dammit! Dammit! Dammit!
• We only had 13 days to go
• We just had the baby shower on Saturday!
• We just bought the last few things at Babies 'r' Us on Monday. He was probably dead by then.
• We were so ready. We'd gotten everything. We bought a cool jogging stroller! We bought a super-awesome safety table of a high chair.
• I never thought my Tuesday would end up like this when I went to bed on Monday night
• He looked so perfect. We've been robbed. He's been robbed.
• The little bugger was too active for his own good
• We were supposed to be having our Caesarian class the next day
• Should we try again? Can I handle seeing Sarah go through all the pain and suffering of another C-section?
• It's just not fair!
• I wouldn't wish this on anyone
• This sucks
• This just isn't fair
• We'll get through this

We've been very grateful for the near endless stream of visitors, phone calls and SMSes, and flowers. It's helped us not dwell on things, especially given all of our family is so far away. Sarah's Mum, who was going to arrive in 5 weeks, is now arriving on Friday, so that'll be good for Sarah. Sarah will hopefully be discharged on Friday or Saturday. We're planning on cremating Joshua, as it just doesn't seem right to bury him over here and then someday move back to Australia and leave him all alone. Current thinking is we won't have a funeral service. Here's what I emailed to the people we were going to send the birth announcement to:

Hi everyone, It is with heavy hearts, that we have to tell you that rather than announcing Joshua's birth on the 17th of September, we have to say that yesterday, we learned that we lost him, 13 days before he was to be delivered. Sarah woke me yesterday morning at about 2:30am, because she'd woken up at about 2am, and realised that she hadn't felt Joshua moving since about 8am the previous day. She tried a few things to get him moving, but they didn't work, so we hurried into Labor & Delivery at the Lucille Packard Children's hospital. There, they confirmed the worst, no heartbeat. Yesterday morning at about 10am, Sarah had a c-section so the doctors could deliver little Joshua. He was absolutely perfect, weighing in at 4 pounds 12 ounces (2.15 kilograms) and 26.7 centimetres (10.5 inches). Yesterday was a very long day. Sarah is currently recovering in the Cardiac Surveillance Unit (CSU) of Stanford Hospital (her aorta has been absolutely fine, the doctors are just being their usual cautious selves). It's a little bit up in the air as to whether she'll spend the entirety of her recovery in the CSU, or if she'll be transferred back to the Post-Partum area of Lucille Packard after 24 hours. (We hope that she does get transferred back, as the CSU isn't really used to dealing with post-c-section patients, particularly ones that have lost the baby). The obstetrician that delivered Joshua said that his umbilical cord was wrapped around his neck twice, fairly tightly, and once around his body. So whilst we'll never know for sure, it looks like it was a cord accident. That's a good enough explanation for us, so we're not going to have him autopsied. That's about all I can report at the moment. If you'd like to speak to Sarah, you can either call home and I'll try to keep Sarah's extension forwarding to her hospital room, or you can call my cell phone. I've got it on vibrate all of the time, and I'll answer if we're not in the middle of something. If you're calling from Australia, my extension at home will let you connect to my cell phone. If you're local, and would like to visit, we'd love to see you, just call ahead to check where we are. It's going to be hard, but we'll get through this.

Great essay from Paul Graham about why college prestige doesn’t matter. (I wish I had both the time and ability to churn out his volume of high-quality writing.) My favorite parts were the following two footnotes:

…No one ever measures recruiters by the later performance of people they turn down.[2]…

[2] Actually, someone did, once. Mitch Kapor’s wife Freada was in charge of HR at Lotus in the early years. (As he is at pains to point out, they did not become romantically involved till afterward.) At one point they worried Lotus was losing its startup edge and turning into a big company. So as an experiment she sent their recruiters the resumes of the first 40 employees, with identifying details changed. These were the people who had made Lotus into the star it was. Not one got an interview.

…Obviously you can’t prove this in the case of a single individual, but you can tell from aggregate evidence: you can’t, without asking them, distinguish people who went to one school from those who went to another three times as far down the US News list. [3]… [3] The US News list? Surely no one trusts that. Even if the statistics they consider are useful, how do they decide on the relative weights? The reason the US News list is meaningful is precisely because they are so intellectually dishonest in that respect. There is no external source they can use to calibrate the weighting of the statistics they use; if there were, we could just use that instead. What they must do is adjust the weights till the top schools are the usual suspects in about the right order. So in effect what the US News list tells us is what the editors think the top schools are, which is probably not far from the conventional wisdom on the matter. The amusing thing is, because some schools work hard to game the system, the editors will have to keep tweaking their algorithm to get the rankings they want.

As an alum of a fairly prestigious institution, I think I endorse Graham’s conclusions.

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Anyone who has done an operating systems 101 course is familiar with the standard hierarchical page-table structure. This is essentially a radix-tree where bits of the virtual address are taken as indexes into an array of pointers, each pointing to the next level down or, at the leaves, to a physical entry. One potential issue with this style of page-table is with a very large, very sparse address space (such as in a single address-space operating system) there will be many intermediate steps with possibly only a single translation at the end (i.e. lots of single pages scattered all around your address-space). Thus we can add a bit-field guard to each of the entries in the page table (Liedtke, 1994) to help indicate only those paths through the tree which are valid (similar to a Patricia tree). Translation first proceeds as usual; the top bits are used as an index into the top level table. However, each entry now contains extra information about further valid addresses. The guard is masked against the next bits in the virtual address; if it matches (e.g. in our example is 0x2) the next step can proceed directly to the leaf node, bypassing the middle look-up. The entry can be marked as either final (i.e. pointing to a leaf node) or intermediate, in which case the process continues with the next level (which also has its own guard, and so forth). Any entry that does not match the guard is known to be false, and therefore a fault can be raised. To examine this further, consider that we know that each page in our 24-bit address space above is 4KiB, thanks to the 2¹² = 4KiB offset. Therefore each of the 16 possible values of the top four bits selects 1MiB of the 2²⁴ = 16MiB address space; e.g. 0x0 selects the first megabyte, 0x1 the second and so forth. The second 4 bits selects a 64KiB region of this 1MiB, and the last 4 bits selects a 4KiB region of this 64KiB region. This scheme could work quite well if we were using only 16 pages each separated by 1MiB. Each of these pages would only require an entry in the top level with an appropriate guard which could then be marked as final and point directly to a physical frame. Once things become less sparse however, we need to start filling in middle levels. If you have 2 pages within a 16MiB region, you need at least one extra bit of address to tell them apart. If you have 3 or 4 pages, you need at least 2 bits to tell them apart, and so forth. It would therefore be beneficial to have variable level sizes to dynamically adapt and create the most efficient lookup possible given the address space layout of a process. For example, if you knew your process was only going map pages 0x123 (100100011) and 0x124 (100100100) a good option would be to make your top-level only two entries (i.e. check the top bit) with a guard on the entry at index 0x1 of 00100. You then need a second level with 8 pointers to differentiate the remaining 3 bits (each of these would be final and hence point directly to a physical page). The more pages you start mapping, the less bits you can discard with the guard. If you follow this through to a guard of 0 bits you end up with a linear page-table. It has been shown (Elphinstone, 1999) that fixed level sizes with 16 entries tends to work well. For a 32-bit address-space with 4KiB pages (e.g. 12 bits offset) this leaves 20 bits to be mapped by the page-tables; with each level mapping 2⁴ bits this means a 5 level tree. The guard values provide enough path-compression that the table is not constantly walked. The disadvantage is that it may "over-allocate" meaning more space is dedicated to page-tables than strictly required. Deciding where and when to split levels, what size indexes to put at each level and updating all the guard values dynamically to make the smallest, most efficient page-table would create a variable-radix page-table (Szmajda and Heiser, 2003). In summary, a guarded page-table is more useful the more sparse your address space is. A variable-radix guarded page-table is complex, but could offer advantages for implementing variable page-size support and thus having positive effects on TLB coverage.

Two words: flawless execution. I can enjoy almost any movie that is well constructed, regardless of genre, plot, etc.. It did help to sit pretty far back in the theater, though. If the CIA were really as clever and technologically sophisticated as it appears in the Bourne movies, the United States wouldn’t have so many foreign policy disasters on its hands (egregious constitutional violations notwithstanding). Technorati Tags: Bourne Ultimatum, Movies, Queasycam

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This week has consisted of fighting registrars and doing a bit of hacking on xen-shell, xen-tools, and the chronicle blog compiler. CJ has done some good work trying to get the code modularised, and I expect between the pair of us we can make things neater and better generally. I've also fixed a couple of bugs relating to the hard-wiring of device names (/dev/sda, /dev/tty1, etc). These devices are replaced in newer versions of Xen which wants to use /dev/xvc0 and /dev/xvd[a-z] instead. There's nothing else happening at the moment; I'm just having a lot of fun laughing at our new kitten sliding around on our polished wooden floor! Chronicle seems to be getting pretty popular which is ironic because it was a quick hack to allow me to post blog entries on a couple of hosted sites - which I've not yet done. Oops. In other news I'm loving the Nintendo DS at the moment, Megan brought me one back from America on her recent trip and I think a day hasn't passed where one or both of us has played less than 30 minutes each. I'm annoyed that Sim City DS only allows us to play with one city - right now it is her turn, and I'll have to wait until she's finished with her creation before I can have a go - because otherwise I'll wipe her city out.. :(

This is the result of Swiss voting on ISO/IEC DIS 29500, the fast-tracking of the Microsoft Office Open XML file format.

4 screen AG	approval
Accenture AG	approval
ADVIS AG	approval
ALTRAN AG	approval
Baggenstos Wallisellen	approval
Bechtle IT-Systemhaus Thalwil	approval
CIS-Consulting	approval
Comsoft Direct AG	approval
Coris SA	approval
Dr. Pascal Sieber & Partners AG	approval
dynawell ag	approval
Ecma International	approval
ELCA Informatik AG	approval
EPFL Lausanne	disapproval
FSFE Free Software Foundation Europe	disapproval
GARAIO AG	approval
Gysel Ulrich Emanuel	disapproval
H.R. Thomann Consulting	approval
Hewlett-Packard (Schweiz) GmbH	approval
HSW Luzern, Institut IWI	approval
IAMCP Switzerland	approval
IBM (Schweiz)	disapproval
Informatikstrategieorgan Bund ISB	approval
isolutions gmbh	approval
itsystems AG	approval
Kull AG	approval
leanux.ch AG	approval
Leuchter Informatik AG	approval
MESO Products	approval
Microsoft Schweiz GmbH	approval
MondayCoffee AG	approval
Namics AG	approval
NEXPLORE AG	approval
Novell (Schweiz) AG	approval
Online Consulting AG	approval
Open Text	approval
PageUp Bern	approval
PC-WARE Systems (Schweiz) AG	approval
Puzzle ITC GmbH	disapproval
SBS Solutions AG	approval
Secunet SwissIT AG	disapproval
SIUG Swiss Internet User Group	disapproval
SKSF	approval
Skybow AG	approval
SoftwareONE	approval
SyGroup GmbH	disapproval
Sylog Consulting SA	approval
Syndrega	disapproval
TheAlternative	disapproval
Trivadis AG	approval
Unic Internet Solutions	approval
usedSoft AG	approval
Verein /ch/open	disapproval
WAGNER AG Kirchberg	approval
Wilhelm Tux (Verein)	disapproval
Würgler Consulting	disapproval
Zürcher Hochschule der Künste	disapproval
Total of voting (75% majority)	43 approval (75.4%); 14 disapproal (24.6%)

A majority with 75% has been reached with one vote. Why do Hewlett-Packard and Novell vote IN FAVOUR for OOXML!?

World News Australia reports that Police forced three tourists to delete photos of a fence. Apparently the officers in question believed that such photos would be a threat to security. It’s interesting to note that the first sentence of the World News Australia report is “Officials say police who forced three tourists to delete photos of a huge security fence erected in Sydney for the APEC summit were not over-reacting” while later in the article it says “The police action against the tourists may have been “over the top” but was necessary, said New South Wales state Transport Minister John Watkins“. So which was it? Was it “over the top” or was it “not over-reacting“. Strangely the World News Australia web site shows a picture of the fence. If this fence is so secret then why are the pictures being published so that millions of people will see it? For that matter why even try censoring the pictures. Censoring the pictures effectively issues a challenge to everyone who has a digital camera and plenty of spare time (which means most university students among others) to get the best photos of the fence (feel free to leave comments with the URLs for your best pics). While this is happening protesters from Real Action On Climate Change have been protesting at the Loy Yang power station, according to their blog posts it seems that they were partially inspired by the APEC meeting. It seems that APEC leaders are keen on nuclear power. If they really believe that nuclear power is safe then maybe they should have their meeting at Maralinga. There would be little effort or expense required to secure Maralinga and it wouldn’t disrupt a major city. :-# But seriously if they wanted a secure location for a meeting with no protesters then an aircraft carrier would make an ideal location. The people who need to attend the meeting could get flown to a carrier that’s off-shore in the territorial waters of one of the countries concerned with a full battle group to deter any other ships from entering the area. It is reported that Sydney whores are expecting to do a lot of business during the APEC meeting. Maybe this is the reason why they wanted to have their meetings Sydney (which is rumoured to have the best brothels in Australia). I wonder if they are planning for a future APEC meeting in Bangkok…

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Well, checking ISO-3166-2 data for my country, I found out that France officially listed the following subdivisions in ISO-3166-2:

• 22 metropolitan regions
• 4 overseas regions/departments
• 96 metropolitan departments
• 2 territorial collectivities
• 4 overseas territories

Thankfully, they didn't list the hundreds of "cantons" and "arrondissements", nor the 36,000 municipalities. Ah, and France is also one of the very few countries that have *more than one* ISO-3166 code as, besides the logical FR, we have GP for Guadeloupe, GF for Guyane, MQ for Martinique, RE for R union, YT for Mayotte, PM for Saint-Pierre-et-Miquelon, NC for New Caledonia, PF for French Polynesia, TF for the Southern French Territories and WF for Wallis et Futuna. Dammit..:-) Even our British friends didn't steal codes for Scotland or Wales...

I’ve been having problems with one of my Xen virtual servers crashing with kernel error messages regarding OOM conditions. One thing I had been meaning to do is to determine how to make a core dump of a Xen domain and then get data such as the process list from it. But tonight I ended up catching the machine after the problem occurred but before the kernel gave OOM messages so I could log in to fix things. I discovered the following issues:

1. 10+ instances of spf-policy.pl (a Postfix program to check the Sender Policy Framework data for a message that is being received), most in D state.


2. All my Planet news feeds being updated simultaneously (four of them taking 20M each takes a bite out of 256M for a virtual machine).


3. Over 100 Apache processes running in D state.

I think that there is a bug with having so many instances spf-policy.pl, I’ve also been seeing warning messages from Postfix about timeouts when running it. For the Planet feeds I changed my cron jobs to space them out. Now unless one job takes 40 minutes to run there will be no chance of having them all run at the same time. For Apache I changed the maximum number of processes from 150 to 40 and changed the maximum number of requests that a client may satisfy to 100 (it used to be a lot higher). If more than 40 requests come in at the same time then the excess ones will wait in the TCP connection backlog (of 511 entries) until a worker process is ready to service the request. While keeping the connections waiting is not always ideal, it’s better than killing the entire machine! Finally I installed my memlockd program so that next time I have paging problems the process of logging in and fixing them will be a little faster. Memlockd locks a specified set of files into RAM so that they won’t be paged out when memory runs low. This can make a dramatic difference to the time taken to login to a system that is paging heavily. It also can run ldd on executables to discover the shared objects that they need so it can lock them too.

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Some good news after all After removing all remaining license issues regarding missing copyright statements or license statements in some files virtualbox is finally in debian unstable. Since I needed the statements in these files and cause of some bugfixes debian ships now an svn version. So this big and important piece of software is now finally official available. To integrate virtualbox in debian I had to remove some sourcecode and therefore virtualbox doesn't contain the Guest Additions (they contain non-free code from e.g Microsoft). The good news here are that in the next version of virtualbox these Guest Additions will be available from the website and can be downloaded automatically with virtualbox. Enjoy it! Thanks to feivel, who sponsored me

My post about Why Hydrogen Powered Cars Will Never Work has received a record number of comments. Some of them suggested that carbon geo-sequestration (storing carbon-dioxide at high pressure under-ground) is the solution to the climate change problem. The idea is that you can mix natural gas or coal gas with steam at high temperature to give carbon-dioxide and hydrogen. Then the carbon dioxide gets stored under-ground while the hydrogen is used for relatively clean fuel. Beyond Zero Emissions has produced a media release about the fallacies expressed in the FutureGen document promoting so-called “clean-coal”, the best content is in their PDF document titled FutureGen Conceptual Design Retort. Note that I did some research to support the preparation of the retort, I am not referencing them to support my arguments but as background information. One overwhealming problem with geo-sequestration for coal based power plants is that it is significantly more expensive than the current coal-fired power plant design. Currently the price difference between coal power and wind power is quite small and there are several technologies that are almost ready for production which will decrease the cost of wind power, it is expected that before so-called “clean coal” becomes viable (they are planning for the first production plants to go live in 2022) the cost of renewable energy will be lower than the current cost of coal power. There is no reasonable possibility of “clean coal” being cheaper than renewable energy. The underground reservoirs that could be used for storing CO2 currently contain brine, which can contain toxic metals and radioactive substances (according to the Bureau of Land and Water Quality in the US). If toxic and radioactive substances need to be pumped out to make room for CO2 then it’s hardly a clean process! The US Geological Survey has an interesting page about volcanic gas. Apparently it’s not uncommon for small animals to be killed when CO2 forms pools in low lying areas. If (when?) CO2 escapes from geo-sequestration the same might happen with humans. They also have a page about CO2 killing trees at Mammoth Mountain! Before I read this I never realised that plants could be killed by excessive CO2. Apparently tree roots need oxygen and CO2 in the ground will kill them. The release of 300 tons of CO2 per day killed 100 acres of trees. The FutureGen trial power plant is designed to support sequestration of over 1,000,000 tons of CO2 per year (that is over 2,700 tons per day). If it leaked at 1/9 that rate then damage comparable to Mammoth Mountain would be the result. Note that the FutureGen trial plant will be a fraction of the size of a real coal power station so an escape of significantly less than 1/9 of the CO2 from a real sequestration plant would have such a bad result. It’s interesting to note that tents and basements are documented as CO2 risks, so I guess we have to avoid camping in areas near power plants! What would happen if a large geo-sequestration project had a sudden failure? IE if the reservoir broke and all the CO2 erupted suddenly? We already have an answer to this question because such things have happened in the past. In 1986 in Cameroon 1.2 cubic kilometers of CO2 gas was released from a volcanic lake, that is 2,400,000 tons (or just over two years of output from the proposed FutureGen plant). It killed over 2000 people. What might happen if 10 years of output from a commercial scale coal power plant was suddenly released into the atmosphere? As far as I know there has been no research on de-sequestration of CO2. If a reservoir is discovered to be unstable after 20,000,000 tons of CO2 have been stored in it, what will we do? Geo-sequestration of CO2 makes nuclear power plants seem safe by comparison.

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