mattfarmer [dot] net » OLPC

First Post

POS — Sat, 22 Mar 2008 05:19:42 +0000

This is my first post from my OLPC. Kind of. I actually wrote up an article earlier in a little bit of haste and was overly critical of a lot of things and so this post is half edit / half addition to that.

Saturday morning, when I finally woke up, I was siked to see hear that I had a package downstairs for me. All the emails that I had received about the OLPC said that I would I would get an email with the tracking number of my package when it shipped and so I was quite disappointed when it was a few days before my trip, and I still hadn’t heard anything.

But there it was, in was! Just in time!

I was convinced that the smaller keyboard wouldn’t bother me, since I was so used to pecking away on my Treo, so I was pretty surprised when I first tried to use it and had to resort 1/2 the time to the ‘hunt and peck’ method. After hacking around on it for a little bit here and there this weekend though, its not so bad. Sometimes it is difficult to hit all the keys on the membrain keyboard, often requiring you to press the key several times before the stroke takes (especially on the larger keys like the spacebar and back-space key), but we’ll see if that passes with time as well. And while we’re on the note of bashing the keyboard. It is most definitely cramped, some keys are missing (caplocks), and a few keys are in different places (I keep hitting the up arrow when I reach for the right shift key), but all and all, its pretty usable.

I had also read somewhere that the OLPC also didn’t come with support for WPA wireless signals which I was frustrated by, but I seemed to be able to join my wireless router with no troubles at all from the network screen.

So at first glace, I was unimpressed to say the least, but after using it for a short while, it definitely seems like it will be worth the money spent. I’d also say that I am most definitely not using this laptop for what it was designed for, and I really don’t see either of these issues being a problem for the intended audiance , and so I’d say the developers of the OLPC should feel as though they did a good job!

How to make an OLPC Application

POS — Sun, 06 Jan 2008 22:53:29 +0000

Someone forwarded me a slashdot article with a link to an IBM article on how to design an application for the OLPC. I haven’t gone to far into it, but it has goes into how to set up QEMU (at least in the simple case), why python was a good language for OLPC to have chosen and then what you need to do. I figured if I didn’t post it here, I’ll be looking for it later, and it might help someone else out so here it is: IBM: Application development for the OLPC laptop.

Making a bigger Harddrive

POS — Sun, 06 Jan 2008 19:41:59 +0000

While using the OLPC under QEMU, I immediately started installing a bunch of development tools into the image. This quickly filled up the 1GB image, and so I wanted increase the size of it.

Originally I tried to dd some space onto the end of it and use parted to expand the image but it gave me an error saying: “Error: File system has an incompatible feature enabled.” And so this is how I got it to work:

Make the newimage:

dd if=/dev/zero of=newimage bs=1GB count=5
Start up QEMU with your OLPC image with this newimage as a 2nd drive:

qemu -m 256 -soundhw es1370 -serial /dev/pts/1 -net user -net nic,model=rtl8139 -hda laptop-orig.img -hdb newimg
From inside the image I then tried to dd /dev/hda to /dev/hdb, but that didn’t work exactly, though I forget now exactly why. It could have been that I needed to re-read the partition table on disk B, but I’m not sure. We still need to do this however for at least the first part of the disk so we get the MBR. (Note: I’m fudging this step to be what I think it should have been, if it doesn’t work, try copying the whole disk)

dd if=/dev/hda of=/dev/hdb bs=4k count=1
Still within the image we want to fdisk the new disk, delete the partition that’s there and make it larger. Technically speaking, if we do this and the partition has the same starting block, I thought that I would be able to still use it (since I had copied the whole disk), but that didn’t seem to be the case.

-bash-3.2# fdisk /dev/hdb

The number of cylinders for this disk is set to 9844.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p

Disk /dev/hdb: 5000 MB, 5000000000 bytes
16 heads, 62 sectors/track, 9844 cylinders
Units = cylinders of 992 * 512 = 507904 bytes

Device Boot Start End Blocks Id System
/dev/hdb1 1 9844 4882623+ 83 Linux

Command (m for help): d
Selected partition 1

Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-9844, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-9844, default 9844):
Using default value 9844

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
So now we have our new disk with the MBR and a good partition table. Now its time to copy over our original image:

-bash-3.2# dd if=/dev/hda1 of=/dev/hdb1 bs=4k
237452+1 records in
237452+1 records out
972604416 bytes (973 MB) copied, 114.234 s, 8.5 MB/s
Now lets make sure that it works:

-bash-3.2# mkdir t
-bash-3.2# mount /dev/hdb1 t -t ext3
-bash-3.2# ls t
activities dev lib mnt proc security sys var
bin etc lost+found ofw root selinux tmp
boot home media opt sbin srv usr
-bash-3.2# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/hda1 913M 716M 189M 80% /
tmpfs 38M 0 38M 0% /dev/shm
/dev/hdb1 913M 716M 189M 80% /root/t
-bash-3.2# umount t

Notice its mounted, and has the same stats as our real system.
Now expand the filesystem to the length of the partition. resize2fs requires that we do an fsck first, so lets do that too:

-bash-3.2# e2fsck -f /dev/hdb1 && !!
e2fsck -f /dev/hdb1 && resize2fs -p /dev/hdb1
e2fsck 1.40.2 (12-Jul-2007)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
OLPCRoot: 22509/118784 files (0.9% non-contiguous), 186946/237452 blocks
resize2fs 1.40.2 (12-Jul-2007)
Resizing the filesystem on /dev/hdb1 to 1220648 (4k) blocks.
Begin pass 1 (max = 30)
Extending the inode table XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on /dev/hdb1 is now 1220648 blocks long.
That should be it. Let’s mount it and see what it thinks!

-bash-3.2# mount /dev/hdb1 t -t ext3
-bash-3.2# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/hda1 913M 716M 189M 80% /
tmpfs 38M 0 38M 0% /dev/shm
/dev/hdb1 4.6G 717M 3.9G 16% /root/t
-bash-3.2# umount t
-bash-3.2# rmdir t

And there we have it! Now we have a 5GB image to play with. I loaded this into QEMU just as I would any other image:

qemu -m 256 -soundhw es1370 -serial /dev/pts/1 -net user -net nic,model=rtl8139 -hda newimg

It booted up just fine! Feel free to download and install away, realizing of course that you won’t be able to ever apply this image directly to your OLPC, but it will at least allow you to develop first and worry about the size of things later on.

One Laptop Per Child

POS — Sun, 06 Jan 2008 18:50:50 +0000

Many of you have probably heard of the One Laptop Per Child [http://laptopl.org] Program or seen their recent commercials for their GiveOneGetOne program on mainstream TV. Well I bit the bullet and decided to get one of these.

Costing $425 (which covers the cost of 2 laptops and shipping to myself), I think its going to work out pretty well. The machine is fairly modest, having only a 433 Mhz CPU, 256 MB of ram, and 1GB of flash rom (for a hard drive). What make this laptop so interesting is the rest of the design. It’s lcd screen was designed specifically for this laptop to be extremely friendly in the low power realm, its case is designed to seal well enough that children walking to and from school need not fear rainstorms and dust, and the battery can charge off of anywhere from 11 to 18 Volts. Add to this that it has built in wifi and an expansion SD memory card slot, and you have a pretty mobile friendly laptop.

One of the first things I’ll do when I get this is find some type of alternative charging source for it. The children that receive these will get some sort of hand crank which should give 10 minutes of use to every 1 minute of charging, but the purchasers don’t get this feature. I’ve already looked at several inexpensive solar cells but have yet to decide on one yet. Until then I’ll just be working on the software in QEMU and seeing what I can do!