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-1.5, XO-1.75 and XO-4 hardware and 13.2.0-13.

Ingredients

• an XO-1.5, XO-1.75 or XO-4,
• a SD card for Swap; minimum size 512 MB, good quality, fast access, e.g. class 10,
• a USB hard disk drive for storing RPMs and build files; minimum size 120 GB, fast, large capacity,

Recipe

• install a recent OLPC OS (we used 11.3.1-17 or 13.2.0-13),
• boot to Sugar or Gnome, log in, connect to network,
• disable automatic power management from the Sugar control panel, or in Gnome:

 sudo touch /etc/powerd/flags/inhibit-suspend

• insert external SD card, and prepare for swap -- in a terminal, as root

 # see what block device id is the external SD, usually mmcblk1p1
 mount | grep mmcblk
 
 # unmount any existing partitions
 umount /dev/mmcblk1p1
 
 # delete manufacturer's partition
 # create a new partition, of at least 2GB, type 82
 parted /dev/mmcblk1
 (parted) rm 1
 (parted) mkpart primary linux-swap 1M -1s
 (parted) quit
 
 # prepare the new partition to be swap
 mkswap /dev/mmcblk1p1

 # the above will report a UUID identifier, such as
 UUID="ff1bfee8-4051-4d53-ba5e-e21559fc3c24"

 # add this UUID to fstab to use swap automatically on every boot
 echo UUID=ff1bfee8-4051-4d53-ba5e-e21559fc3c24 swap swap defaults 0 0 >> /etc/fstab
 
 # enable all swap partitions in fstab
 swapon -a -v 

• prepare the USB hard drive, 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 10:27:03"

• on 11.3.x, 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
• on 11.3.x, 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

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

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

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

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

• 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 make the first build:

 sudo ./osbuilder.py examples/olpc-os-13.2.1-xo4.ini

The first build will take much longer than subsequent builds, because the disk cache is empty.

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, 13.7 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 43 minutes.

# time ./osbuilder.py examples/olpc-os-13.2.0-xo1.75.ini
...
real    43m13.025s
user    23m44.010s
sys     4m17.620s

Configuration file: http://dev.laptop.org/~quozl/z/1V3xjq.txt

Hardware performance measurements:

• internal eMMC, sequential read, 27.8 MiB/s, (operating system),
• internal eMMC, filesystem write, 7.38 MiB/s,
• USB HDD, sequential read, 27.5 MiB/s, (osbuilder filesystem),
• USB HDD, filesystem write, 27 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)