OS Builder/Run on XO hardware

It is usually possible, if a bit slow, to run OS builder on XO hardware. On platforms where fast machines are available (such as x86), using a server-class "builder" machine is recommended.

When resources are limited, or if server-class machines are not available for the platform (such as ARM), this recipe is recommended.

The procedure has been tested with XO-1.75 and XO-4 hardware and builds of the 11.3.x series and 13.2.x series.

Ingredients

• XO-1.75 or XO-4
• Good, fast SD card for swap,
• External USB HDD -- fast, large capacity, to store cached RPMs and build files,

Recipe

• Install a recent OS (we used 11.3.1-17 or 13.2.0-8)
• Boot to Sugar or Gnome, log in, connect to network
• Disable automatic power management from the Sugar control panel, or in Gnome:

 touch /etc/powerd/flags/inhibit-suspend

• Insert external SD card to be used for swap
• Prepare the SD for swap -- in a terminal, as root

 # see what block device id is the external SD
 mount 
 
 # unmount any existing partitions
 umount /media/mysdcard
 
 # delete manufacturer's partition
 # create a new partition, of at least 2GB, type 82
 parted /dev/mmcblkN
 (parted) rm 1
 (parted) mkpart primary linux-swap 1M -1s
 (parted) quit
 
 # prepare the new partition to be swap
 # it will report a UUID identifier
 mkswap /dev/mmcblkNp1
   
 # add this line to fstab to use swap automatically on every boot
 echo UUID=<UUID reported by mkswap> swap swap defaults 0 0 >> /etc/fstab
 
 # enable all swap partitions in fstab
 swapon -a -v 

• Prepare the USB HDD partitioning it with a large partition of type "83", then use mkfs to create an ext3 or ext4 partition.
• Ensure the system date is correct, set it if necessary:

 date --utc --set="2024-07-25 15:13:06"

• Follow the OS Builder development installation instructions -- remember to disable firstboot, and note that you will want to have your OS Builder directory on the external USB disk
• move /var/tmp to the USB HDD; because some large files are created:

 D=/run/media/olpc/DISK/var/tmp
 mkdir -p $D
 cp -pr /var/tmp/* $D
 mount -o bind $D /var/tmp

• For 11.3.x, we want to work on branch v4.0, so

  git checkout -b v4.0 origin/v4.0

• For 13.2.x, install the olpc-os-builder package:

sed -i '/excludedocs/d' /etc/rpm/macros.imgcreate
yum install olpc-os-builder

• During test builds, generating only one image is faster -- edit examples/olpc-os-11.3.1-xo1.75.ini to disable 8GB image generation and comment out the "usb_update" module.

Your setup is ready, you can now do:

 sudo ./osbuilder.py examples/olpc-os-11.3.1-xo1.75.ini

Experiences

2013-07-29, XO-4, 2GB RAM, 4GB SWAP, 500GB USB HDD, 13.2.0

Build took 31 minutes.

# time ./osbuilder.py examples/olpc-os-13.2.0-xo4.ini
...
real    30m55.275s
user    12m42.790s
sys     2m8.370s

Configuration file: http://dev.laptop.org/~quozl/z/1V3fiW.txt

Hardware performance measurements:

• internal eMMC, sequential read, 49 MiB/s, (operating system),
• internal eMMC, filesystem write, 17 MiB/s,
• USB HDD, sequential read, 27 MiB/s, (osbuilder filesystem),
• USB HDD, filesystem write, 27 MiB/s,
• external SD, sequential read, 15 MiB/s, (swap),

Performance tweaks:

• versioned_fs=0
• make_tree_tarball=0
• no sugar
• a warm file cache (timing of a subsequent run, not an initial run)

2013-07-30, XO-1.75, 1GB RAM, no SWAP, 500GB USB HDD, 13.2.0

Build took n minutes.

# time ./osbuilder.py examples/olpc-os-13.2.0-xo1.75.ini
...

Configuration file:

Hardware performance measurements:

• internal eMMC, sequential read, n MiB/s, (operating system),
• internal eMMC, filesystem write, 9.2 MiB/s,
• USB HDD, sequential read, n MiB/s, (osbuilder filesystem),
• USB HDD, filesystem write, n MiB/s,

Performance tweaks:

• versioned_fs=0
• make_tree_tarball=0
• no sugar
• a warm file cache (timing of a subsequent run, not an initial run)

2013-07-30, XO-1.5, 1GB RAM, no SWAP, 500GB USB HDD, 13.2.0

Build took 39 minutes.

# time ./osbuilder.py examples/olpc-os-13.2.0-xo4.ini
...
real    38m50.632s
user    21m16.550s
sys     2m58.560s

Configuration file: http://dev.laptop.org/~quozl/z/1V3vxy.txt

Hardware performance measurements:

• internal microSD, sequential read, 18.2 MiB/s, (operating system),
• internal microSD, filesystem write, 6.23 MiB/s,
• USB HDD, sequential read, 32 MiB/s, (osbuilder filesystem),
• USB HDD, filesystem write, 29.4 MiB/s,

Performance tweaks:

• versioned_fs=0
• make_tree_tarball=0
• no sugar
• a warm file cache (timing of a subsequent run, not an initial run)