Recent blog entries for katzj

More Fedora on XO

So, you just got your XO to do some testing of Fedora on OLPC. You update the software that was on there, get a developer key, wait a day, and then get all ready to boot your Fedora image off of the SD card ....

And it boots. But it's slow. Very very slow. Some slowness is to be expected... this isn't a fast machine. But it should probably be a little bit speedier than it is. So want to try out a few experiments to try to help pin down the cause of the slowness? Then read on, pick a case and leave comments about your results.

1. Try using a persistent overlay instead of the in-memory one. Add --overlay-size-mb to your livecd-iso-to-disk invocation. Amount should be relative to the size of your SD card.
2. See if/how much having swap available helps. You can create a file on the SD card with dd, run mkswap against the file and then enable it on the XO. The best test for this would probably be to boot the XO single-user and run swapon from there and then do telinit 5.
3. Try disabling some services from the live image. Again boot to single-user, chkconfig some services and then telinit 5
4. ... your idea here. Hopefully other people have some ideas of things to try as well. Try them out and let us know how it goes.

Syndicated 2008-10-08 15:56:50 from Jeremy's Thoughts

More racing skills

Both days of this weekend had a skills clinic for the MIT racing team and I went to both. Again, the clinics were held down at the Wells Ave office park. I think at this point, I have the way from MIT to that part of Newton etched into my memory. Which also means I can get from MIT to various points around Brookline and Allston with relative ease.

Yesterday's clinic was focused on improving cornering skills. This is something which, especially after going through it, is incredibly useful and an area where I really had no clue what I was doing technique-wise. Sure, you can turn the bike and go around a corner, but being able to do so in a way that's both fast and safe is an entirely different story. There's quite a bit of technique to it. But it's cool to have a better idea of how the pros manage to severely tilt their bikes when going through corners of a crit at speed. It's an area where I'll want to spend some time practicing the technique to really get it down to where I don't have to think about it. After that, we followed up with another rousing game of Death Bike. Which was, again, a good time.

Today was focused on sprinting and riding in a pack. Again, a little bit of being told a "good" way of doing things seems like it will go a long way. But sprinting form feels like it's going to be a lot more difficult for me to get "right" just due to having to break bad habits. Luckily, sprint intervals are a pretty easy thing to do and a good way to work on the form. For riding in a pack, there was a bit of focus on moving up and how to do so quickly and efficiently. The fact that we were doing this at Wells Ave was interesting; I've raced there enough times that I know how various things feel and so it was interesting to do things in a different way. In the past I've mostly moved up by going to the outside, applying some power and getting to the front. While this does work, it's pretty inefficient as it ends up meaning I leave the draft. I've now got a much better idea on how to move up through the pack and save energy. Which should end up helping at the end for the sprint. We finished out the day with a game of Bike Capture the Flag which ended up being pretty fun as well.

All in all, a good two days of work. And although my distances were lower than my normal for a weekend, I feel like I got quite a bit out of both days and am pretty tired from both as well. This week will be an easy-ish week on the riding side so that I can be in good shape for racing at Jamestown next Monday. But that's okay, as it's a busy week on pretty much every other front. Especially since I didn't do any homework this weekend. So, it'll be a bit of a scramble to get that taken care of, but it doesn't look like it'll be too bad.

Syndicated 2008-10-06 02:54:41 from Jeremy's Thoughts

More Fedora on XO progress

Made some more progress today with running Fedora on the XO. Until I manage to go and pick up the right SD card, I figured I'd give performance a little bit of a rest and so instead focused on seeing which bits of the hardware appeared to work (or not). So I booted up into run-level 3 with the image I posted last night and started poking.

• Wireless: First thing to check was the wireless to see if it worked. And it does, the driver gets loaded, we have the firmware and it managed to find the access point at my house and associate without problems. Haven't really looked at mesh at all, and also haven't dived into making sure wpa works, but at least for the basics, it seems okay.
• Camera: From the quick test of "does the driver load" and "does the driver give data", this looks okay too. Doing cat < /dev/video0 as a user turns on the LED for the camera and prints garbage to the screen.
• Sound: Driver loads and the mixer shows elements, but playing sound isn't looking like it's working. Needs more investigation
• Internal Flash (NAND): Driver seems to load and with a couple of pointers from dwmw2, is mountable without having to do any more module loads. Went ahead and did the next obvious step and changed things so that we can use that for the persistent /home.
• Special keys: Most of the keys on the keyboard seem to be appropriately mapped, but there are some that will need mapping via hal. Should be straight-forward to sit down and do as it's just writing some fdi file bits (hint: if someone wants to volunteer to do this, I can point you in the right direction :)
• Power management: Suspend to RAM isn't showing up as available at all right now. I suspect some kernel bits that haven't been upstreamed need to be pulled out. Will probably look closer at this tomorrow

And now, I think it is time to go watch some tv

Syndicated 2008-10-03 03:13:05 from Jeremy's Thoughts

New Fedora on the XO Test Image

A new image for testing Fedora on the XO is now available. This image runs quite a bit slower than the previous one in X and I haven't gotten to why yet, so if you try it, I recommend quite a bit of patience. But I wanted to get something up in the near-term so that people would see some sort of progress :-)

Changes and improvements in this image...:

• Updated packages to match those that are included in the Fedora 10 beta that was released yesterday
• Slightly newer kernel (the one that davej built last night) which has debugging disabled. Sadly, this wasn't the help I hoped it would be.

Booting to runlevel 3 is okay for at least some testing, though. So be sure to add --extra-kernel-args 3 to your invocation of livecd-iso-to-disk in addition to passing --xo. And hopefully we'll have a new image up shortly that fixes some of the slowness and makes things more reasonable for general use "soon"

Syndicated 2008-10-01 21:50:59 from Jeremy's Thoughts

Progress with the end of seasons

This was the last weekend of summer and on Saturday, it actually felt a bit like fall was already here. I went out with the MIT cycling club on their ride to Dover (MA). Was a nice route and largely in areas that I had never been before, which was good. Relaxed pace and a good opportunity to talk with and start to get to know some of the other people riding. Was glad that I had picked up some knee warmers, though, as they were pretty much the perfect extra layer. Yesterday, though, felt more like summer again as I went out on the Quad ride. Again a beautiful day, though, and nice to get some more good riding in.

Today brought the actual beginning of autumn and waking up to it being kind of dull, gray and cool was not the way I had hoped to start the morning. But I dragged myself out of bed and headed to the office for a day that I had somewhat booked already with meetings.

Between them, managed to get the serial cable hooked up to the OLPC in the office and started with trying to track down kernel things again. And finally started getting somewhere. After a week (plus) of dead ends, I happened upon the right avenue and was able to confirm that the problem was OpenFirmware loading the initrd into RAM where it shouldn't have been. Wrote up a good description of what was going wrong, sent it off, and Mitch Bradley (aka OFW Ninja) had me a fix in about an hour. I didn't see it for a while longer due to other meetings, but it was in my inbox.

So, after getting home and having dinner, I tried it out and was greeted with success. So modulo fixing some more "normal" kernel problems, it looks like we should be well on our way to having the XO able to boot with the regular Fedora kernel. And this means that having an XO run just any old Fedora live image is now a very big step closer to reality...

Syndicated 2008-09-23 02:21:26 from Jeremy's Thoughts

Catching up

About this time last week, I came to the realization that I had a ton of pending work to get done. Luckily, I'm now starting to feel more like I'm on track and not behind. But it was less than fun, so I'm definitely going to try to be better about staying on top of things, especially the system architecture "opportunity sets" for the rest of the semester. Otherwise, classes are going good. Given the amount of time getting sucked up, I decided to not actually be a listener for the Software Systems Engineering course, which is too bad. But this way, I should have some time to just to a few more random talks around MIT. Which is probably going to be more interesting and helpful.

On other fronts, the Fedora on OLPC and Sugar on Fedora efforts are picking up steam a bit. Hopefully we'll have some more useful milestones for both in the next week or so. But due to work there, I haven't had much time to spend on getting a SIG for other smaller form factor machines (including netbooks, the XO and more) underway. Luckily, Peter Robinson has volunteered on fedora-devel-list to help get this off the ground, so hopefully we can get that going to.

Never a dull day...

Syndicated 2008-09-18 22:46:34 from Jeremy's Thoughts

MIT Racing Skills Clinic

One thing that I've told myself I'm going to try to take more advantage of than I did in the spring is some of the other things that MIT has to offer. This includes trying to make a point of going to some random lectures on random topics (... that seem interesting) but also doing some riding with the MIT cycling club/team. I went on a few of the Intercollegiate Ice Cream rides over the summer and the people seemed nice enough. So I went to the first meeting of the semester on Monday and decided that I am going to do some collegiate racing for MIT in the spring. I figure that a) it's a good chance to get some more riding in b) a good chance to meet some more people from different parts of MIT than I usually interact with as an SDM-er and c) the MIT racing team is good. Very very good. As in, nationals champion good.

Anyway, the first skills clinic of the year was held yesterday so I went down for it. Not a lot of mileage put in, but a good workout. And lots of good work. The MIT team is coached by Nicole Freedman and it's pretty obvious even after one skills clinic that one thing that has helped the team succeed is a good coach. The first skills clinic was a lot of fun -- some things to help focus on relaxing (somewhat ironic, yes), some skills drills and then some "getting comfortable riding really really close to someone". The latter culminated in a fun game of Death Bike. Yes, Death Bike is as much fun as it sounds and I'll have to be sure not to miss the first skills clinic next year so that I can do it again ;-) Looking forward to the future clinics as I think they'll be very helpful to me in getting to be a better rider and racer.

Today brought rain and quite a bit of it, so I didn't get out for a ride and have instead spent the day working either on stuff for work or on stuff for school. While I would have liked to have gotten a ride in, at least I can be glad that I was productive and thus feel better if I take some time for a ride on a day with better weather :-)

Syndicated 2008-09-15 00:18:10 from Jeremy's Thoughts

One week of classes and then a little

One week of classes is now complete so I figure it's about time to put up my first impressions of what I'm taking.

The first sort of general impression is that after a pretty busy summer semester I'm not really ready for things to be picking back up for the fall yet. I realized on Thursday that I've been a bit lax ingetting together groups for classes this semester and this also put off starting on some assignments. The first of which are all due this week. But got that under control and have spent some time this weekend to get back on track and will hopefully be done doing so with some concerted effort today. As for the specific classes I'm taking three for credit - two of the required and core classes for the SDM program and one elective

The first of the required classes is Systems Program Management. The course, as with a number of the ESD courses is taught by a few faculty members. Overall it looks like it should be okay and the professors definitely seem to be good. My one complaint thus far is that there is a non trivial amount of repeating, albeit at a less in-depth level, of the materials presented in System Dynamics. If it is seen as important enough to be covered either the course should be required or the sequencing adjusted a bit so that the intro material gets covered in SPM and then the SD class could spend more time on deeper aspects of the material.

The second of the required classes I'm taking is System Architecture. Crawley seems a bit less antagonistic than in January, at least thus far. And an attempt is being made to help make this more relevant to software -- we'll see how it goes.

The elective I'm taking is the Sloan Business Law course (15.616). I'm actually enjoying this quite a bit and think that it's going to be a very useful course. We're starting out with a bit of whirldwind tour through some of the basics of tort law, some regulation and criminal law, and contracts. Then, a vast majority of the rest of the course is taken up by guest lectures from practicing experts in a variety of legal fields. The readings have thus far been relevant and a reasonable length. And the professor is also very engaged and clearly wants to help drive some understanding of the material.

In addition to those three, I'm intending to be a listener (MIT-speak for auditing) for the new Software Systems Engineering course which is being run as a trial this fall. The big picture overview of the class made it seem like there's an attempt being made to bring in a lot of the big system-specific pieces for the software world. It should at the very least be interesting to give some feedback on the various pieces and hopefully help make the SDM program a bit better for software people in future years.

Syndicated 2008-09-14 19:47:19 from Jeremy's Thoughts

Glimpse of Fall

We've started to have our first glimpse of fall here in New England as the temperatures started to drop yesterday. And this means the start of the time of layering and digging out all of my cooler weather gear for commuting. I'm interested to see how long my Keen Commuter sandals are effective when worn with wool socks. Actually, a lot of my wardrobe this time of year starts to bring in wool -- it's a great fabric to keep you warm when it's cooler in the mornings and evenings but at the same time, it doesn't have to be overbearingly warm in the middle of the day. So I think that my Earth, Wind and Rider wool jerseys are going to start seeing quite a bit of use again.

Syndicated 2008-09-11 15:37:08 from Jeremy's Thoughts

Fedora on an XO

As I mentioned before, one thing that I've been spending some time on is getting a "stock" Fedora to run on the OLPC XO hardware. Obviously there's not a CD drive, but there is a USB port and there is also an SD card slot. Which given the support in our live images for running off of such things, there seemed to be a bit of an obvious matchup.

There's just one (large-ish) problem. The XO is a Geode, so an i586 processor with cmov. So the stock i686 kernel on the live images definitely doesn't boot there. Unfortunately, neither does the i586 kernel. I'm working on tracking down what the relevant configuration difference is so that it can be fixed -- interestingly enough, if you don't load an initrd, a Fedora i586 kernel can boot fine. So there's definitely something a little odd going on. If you have experience in debugging early boot of an XO and have any tips, leave a comment or catch me on IRC or send me mail :)

So, instead I've done a modified version of the main OLPC kernel with the help of sdziallas that includes squashfs and also turns on things like dm-snapshot which we need for live images.

That plus a pretty straight-forward image config and we can build a live image that boots into the GNOME desktop on the XO off of either an SD card or a USB stick. There are definitely still things to be fixed, though. To try to help some of that, I've created a tracking bug that can be used by those who have an XO and try running a Fedora live image on it.

Do you have an XO and are interested in trying it out? If so, first be sure that you have a developer key for your system. Then, you can download an image based on today's rawhide (debranded) from here. I've basically tested that it boots, logs in to the desktop and associates to my access point. Then gpk-update-icon fires up and we run out of memory for things. If you kill it quick enough, then you can fire up firefox and slowly do a little bit of other stuff.

Some things that are continuing to be worked on:

• Having somewhere to swap would help a lot
  
• Using the SD card/USB stick for your persistence instead of eating up valuable RAM
  
• Persistent /home on the internal NAND (jffs2)
  
• Looking at high memory usage things and helping to make them better
  
• Fixing the standard kernel so that we can boot it on the XO
  
• And if we do the last one then we can boot the standard live images, any of them, on the XO
  

Any help appreciated! Any bugs you find, please be sure to make them block the tracker so that we can keep up with them accordingly.

As for the questions about what the end goal is here -- ultimately, I'd like to have any Fedora spin working on the XO just like it works on lots of other hardware. For Fedora 10, this may be a stretch (although I'm going to land any small changes that can be identified in that timeframe even though it's not a feature and we're at feature/beta freeze). But for Fedora 11, it should certainly be doable.

Syndicated 2008-09-11 02:26:47 from Jeremy's Thoughts