The Balloon Board project set out more than a decade ago to produce a high-performance, low-power, open hardware embedded Linux computing platform. It successfully did that, and now thousands of them are in use in all sorts of products all over the world.

One of the major achievements of the project was a build system which could configure, download, patch and build a boot loader, kernel and root filesystem using a relatively simple menu-driven interface. The menu allows the user to select which type of board to build for, and which customisations to apply. These can include custom kernel drivers for a particular application, or a different Linux distribution (Debian and Emdebian are supported). It doesn’t need an especially powerful machine to run on, but can make use of multiple CPU cores to speed up building.

My colleague Nick Bane has recently, in collaboration with Cambridge University Engineering Department, updated the build system so that it can build software for the Raspberry Pi and BeagleBone Black, both of which are somewhat newer hardware than the Balloon Board. This should make it easier to port software and device drivers between the boards without having to start with a completely new development system.

It might also be of interest to developers working with the Raspberry Pi and BeagleBone boards who want a simple, repeatable way to create the necessary software. This is especially important for use in manufactured products, where the process for creating a whole software distribution needs to be well understood.

This page describes my first attempts at building Debian Linux and the kernel for the BeagleBone Black. This is extremely preliminary, and it doesn’t work yet,

Software build options

Get the software:

svn checkout svn://balloonboard.org/balloon/branches/menuconfig2
make menuconfig

• Mode Expert mode
• Balloon Board BeagleBone Black
• Choose which buildroot version to build -> Feb 2013
• Select kernel version 3.8

• make kernel-menuconfig

• Select Kernel Features -> unselect Compile the kernel in Thumb-2 mode

• make buildroot-menuconfig

• Package Selection for the target -> Hardware handling -> Misc devices firmwares -> unselect rpi-firmware
• Hardware handling -> unselect rpi-userland
• Debian rootfs
• Select kernel and module installation method -> Build Debian rootfs with kernel modules

make

Create Micro SD card

I used a 2GB card in a USB card reader connected to my Debian Squeeze PC. I created two partitions using fdisk. Partition 1 is a 50MB FAT16 (type 6) partition, and partition 2 is the rest of the card formatted as ext3 (type 83). On my system, the card appeared as /dev/sdc.

sudo mkfs.msdos /dev/sdc1
sudo mkfs.ext3 /dev/sdc2

Copy the files MLO, u-boot.img and uEnv.txt from the BeagleBone USB drive to the FAT partition.

Make uboot image

sudo apt-get install uboot-mkimage

In build/kernel, do

mkimage -A arm -O linux -T kernel -C none -a 0x80008000 -e 0x80008000 -n "Linux" -d ImageBoot uImage

copy uImage into /boot on ext3 partition

copy am335x-boneblack.dtb from /boot on the original BeagleBone Black board into /boot on ext3 partition

The board tries to boot, but kernel dies with a stack dump:

## Booting kernel from Legacy Image at 80007fc0 ...
 Image Name: Linux
 Image Type: ARM Linux Kernel Image (uncompressed)
 Data Size: 8750560 Bytes = 8.3 MiB
 Load Address: 80008000
 Entry Point: 80008000
 Verifying Checksum ... OK
## Flattened Device Tree blob at 80f80000
 Booting using the fdt blob at 0x80f80000
 XIP Kernel Image ... OK
OK
 Using Device Tree in place at 80f80000, end 80f88bac
Starting kernel ...
[ 0.113797] platform 53100000.sham: Cannot lookup hwmod 'sham'
[ 0.114013] platform 53500000.aes: Cannot lookup hwmod 'aes'
[ 0.114792] omap_init_sham: platform not supported
[ 0.114807] omap_init_aes: platform not supported
[ 0.156004] omap2_mbox_probe: platform not supported
[ 0.225933] Unhandled fault: external abort on non-linefetch (0x1028) at 0xf4
[ 0.233938] Internal error: : 1028 [#1] SMP ARM
[ 0.238662] Modules linked in:
[ 0.241861] CPU: 0 Not tainted (3.8.0 #1)
[ 0.246424] PC is at rtc_wait_not_busy+0x14/0x50
[ 0.251241] LR is at omap_rtc_read_time+0x10/0xa4
[ 0.256147] pc : [<c03eee84>] lr : [<c03ef490>] psr: 40000193
[ 0.256147] sp : df053d60 ip : 00000000 fp : c08b0f28
[ 0.268112] r10: df053e18 r9 : c07d31e4 r8 : df2b7000
[ 0.273560] r7 : df2b71c8 r6 : c08b0f28 r5 : c083a9cc r4 : 00000000
[ 0.280365] r3 : f9e3e000 r2 : 00000000 r1 : df053dc4 r0 : df101010
[ 0.287172] Flags: nZcv IRQs off FIQs on Mode SVC_32 ISA ARM Segment kel
[ 0.294880] Control: 10c5387d Table: 80004019 DAC: 00000015
[ 0.300873] Process swapper/0 (pid: 1, stack limit = 0xdf052240)
[ 0.307134] Stack: (0xdf053d60 to 0xdf054000)
[ 0.311684] 3d60: df053dc4 df053dc4 df053dc4 c03ef490 df2b7000 c03ebbd8 c08b0
[ 0.320217] 3d80: df2b7000 c03ec884 00000000 00000000 00000001 df053dc4 00004
[ 0.328746] 3da0: df053df4 c084fcd4 60000113 df2b54b0 00000000 00000000 80000
[ 0.337275] 3dc0: c084fcc4 00000000 00000000 00000000 00000000 00000000 00000
[ 0.345805] 3de0: 00000000 00000000 00000000 c084fe34 c08b0f28 00000000 00000
[ 0.354335] 3e00: 00000000 df101010 c07d31e4 df103640 c08b0f28 c03eba44 dfef0
[ 0.362866] 3e20: 60000113 df101080 df101010 60000113 00000004 60000113 0000c
[ 0.371394] 3e40: df101080 df101000 df101010 c08b0f30 df104cc0 c08b0f2c c07f8
[ 0.379923] 3e60: 00000000 df101044 df2ccb80 c084fe78 c084fdf4 df101010 df104
[ 0.388453] 3e80: c084fdf4 c08af648 c07d31e4 c07ddb14 00000000 c031e1cc c084c
[ 0.396982] 3ea0: df101010 df101044 c084fdf4 c031cf88 df052000 c031d014 00008
[ 0.405510] 3ec0: c084fdf4 c031b66c df045478 df104c80 df052000 df001840 df2c4
[ 0.414040] 3ee0: c0841ea0 c031bf14 c0725ca0 c084fde0 c084fdf4 c084fde0 c0847
[ 0.422570] 3f00: c0860608 c031d5fc c0860608 c084fde0 c07ddb4c 00000007 c086c
[ 0.431102] 3f20: c07ddb4c c07eff94 c07ddb4c c0008858 00000006 00000006 c0780
[ 0.439633] 3f40: 00000000 c07efcac c07eff94 c07ddb4c 000000dd c086060c c07a4
[ 0.448163] 3f60: c0860600 c07ac314 00000006 00000006 c07ac3f0 c0cc8d80 c0570
[ 0.456693] 3f80: c0577e98 00000000 00000000 00000000 00000000 00000000 00004
[ 0.465222] 3fa0: 00000000 00000000 c0577e98 c000e6d8 00000000 00000000 00000
[ 0.473751] 3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000
[ 0.482280] 3fe0: 00000000 00000000 00000000 00000000 00000013 00000000 b637d
[ 0.490833] [<c03eee84>] (rtc_wait_not_busy+0x14/0x50) from [<c03ef490>] (om)
[ 0.500636] [<c03ef490>] (omap_rtc_read_time+0x10/0xa4) from [<c03ebbd8>] (_)
[ 0.510257] [<c03ebbd8>] (__rtc_read_time+0x58/0x5c) from [<c03ec884>] (rtc_)
[ 0.519423] [<c03ec884>] (rtc_read_time+0x30/0x48) from [<c03ecad4>] (__rtc_)
[ 0.528773] [<c03ecad4>] (__rtc_read_alarm+0x1c/0x290) from [<c03eba44>] (rt)
[ 0.538858] [<c03eba44>] (rtc_device_register+0x140/0x268) from [<c07d3358>])
[ 0.548850] [<c07d3358>] (omap_rtc_probe+0x160/0x3b8) from [<c031e1cc>] (pla)
[ 0.558576] [<c031e1cc>] (platform_drv_probe+0x1c/0x24) from [<c031cdec>] (d)
[ 0.568657] [<c031cdec>] (driver_probe_device+0x80/0x21c) from [<c031d014>] )
[ 0.578459] [<c031d014>] (__driver_attach+0x8c/0x90) from [<c031b66c>] (bus_)
[ 0.587902] [<c031b66c>] (bus_for_each_dev+0x60/0x8c) from [<c031bf14>] (bus)
[ 0.597431] [<c031bf14>] (bus_add_driver+0x178/0x23c) from [<c031d5fc>] (dri)
[ 0.606963] [<c031d5fc>] (driver_register+0x5c/0x150) from [<c031e58c>] (pla)
[ 0.616948] [<c031e58c>] (platform_driver_probe+0x1c/0xa4) from [<c0008858>])
[ 0.626936] [<c0008858>] (do_one_initcall+0x2c/0x164) from [<c07ac314>] (ker)
[ 0.637019] [<c07ac314>] (kernel_init_freeable+0x108/0x1e4) from [<c0577ea4>)
[ 0.646648] [<c0577ea4>] (kernel_init+0xc/0x164) from [<c000e6d8>] (ret_from)
[ 0.655452] Code: e59f6038 e59f5038 e3a04000 e5963000 (e5d32044)
[ 0.661858] ---[ end trace 33e6cc13d62fdb11 ]---
[ 0.666954] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0b
[ 0.666954]