Public message to mr. Fabrice Bellard, author of qemu

Mr. Bellard, I think that I have found a bug in the version 0.8.0 of qemu. I'm testing a custom kernel and when qemu encounters the clflush instruction it just hangs. Contact me if you are interested in details. I guess you can find my email address easier than I could find yours.

Rationale: I'm sick and tired of damned forums and mailing lists. Mr. Bellard didn't leave his contact details anywhere on qemu's web site or in the source files. I wanted to report this bug, but it seems that I have to post it on some qemu forum/mailing list for which, of course, I have to first register. I'm sick and tired of those bloody registrations which I use only once and never again. So if he sees this message OK, if not, well.. his problem.

Oh yes, please, if some of you are subscribed to the qemu's forum or mailing list, I would appreciate it if you draw mr. Bellard's attention to this post.


IT Underground report

Yesterday afternoon I returned from the IT Underground conference in Prague, where I was an invited speaker. I gave a talk on the possible exploatations of smart-cards, and, well, I amazed myself. I had only 16 slides and was a bit worried what am I going to talk about during the two hours planned in the agenda. In the end I had no problem talking and also gave a small demonstration of stealing data from applications.

The conference was very well organized - kudos to the orgranizers. It was held in the Hotel STEP, in the outer part of the town. The hotel was new, modern and pleasant to stay in (except that shower cabins in the bathrooms were a bit small). The hotel was within 10 mins of walking to the nearest metro station, and with Prague's excellent public transport system, it was easy to get to the centre of the city to look around a bit and taste Czech excellent cuisine and beer (for those who will visit Prague: garlic soup (nb! NOT onion soup) is a must to try). Prague is a beautiful city, and I was a bit nostalgic when I had to leave. And extremely cheap, compared Oslo. I could get used to living there very quickly.

To me (and to the most of the audience, I believe) the most impressive lecture was Shawn Merdinger's on vulnerabilities of VOIP phones. I couldn't believe how vulnerable those phones are. Shawn investigated 11 different phones so far, and all of them had some security flaw - either open HTTP, remote debugging, telnet shell, etc. He gave a live demonstration of telnetting onto a VOIP phoe, getting a shell and instructing it to make a phone call to another number. When you answer the other phone, you can listen to whatever the first phone transmits. An ideal spying device! Passwords? What passwords? Except maybe some default and well-known ones.

I made contacts, learned some interesting stuff, and had fun with some cool people. To put it shortly: it was great :)


Linux is stupid..

I'm not saying that other OS'es (*BSD) aren't in this respect since I haven't tried, but here goes my annoyance.

I'm developing a kernel bootable by grub. The floppy image file is formatted to FAT32 and mounted on some directory. When I want to test a new version of the kernel, I copy the kernel executable file to the directory where the floppy image is mounted and run bochs. However, the change is not propagated to the underlying floppy image file! Bochs still runs the old kernel version. I have to explicitly type "sync" in order for the change to be flushed to the floppy image file.

Doesn't linux globally maintain data consistency? Are its FS buffers per filesystem? Why is it done in such a stupid way?

Gmail chat

Heh, when gmail chat is enabled for your account, it first asks you whether you want to have saved and searchable chat histories. I have answered no. BUT.. Should we trust them that they really respect our choice? They might still collect all our personal chats, but just not displaying them. What do you think? Do they really respect our privacy or just pretend to do so?



A time for...

I've discovered when I should clip my fingernails: when I start to accidentaly injure myself to the blood. Nothing serious, but still annoying. This triviality reminded me of an old song (could be 60-ies style, as far as I remember the music) whose refrain had verses in the lines of "a time to love", "a time to breathe",.. I can't remember exactly. I'm kind of fond of the song, so can anyone help me find the song?

While I was writing this text, I remembered the key phrase by which I found the song on the Google. It's Wilson Phillips: "Turn! Turn! Turn! (To Everything There Is A Season)".

What turned out to be more surprising is that the song is heavily based on Ecclesiastes 3:1-8. The original text is reproduced here.

For some reason, this song moves me...



A simple puzzle

A short post after a loong pause. This means that I'm very busy with other stuff.

I am attending a course about formal verification of systems. The book we use in the course gives an example of the "best" (as claimed by the author) way to parallelize a simple task on 2 CPUs: finding the maximum element in a vector of n elements. The problem with their proposed solution is that it is, IMO, far from the "best". I took me only few moments to think up a solution simpler than the one in the book.

The puzzle for my readers: suggest a way to parallelize the above-mentioned task to 2 CPUs. If you want a bigger challenge, generalize to k CPUs.