1 Introduction
2 ------------
3
4 NanoPayload is a test of bootable payloads for the Ben NanoNote, exploring the
5 necessary initialisation activities to allow programs to run on the device.
6 Unlike U-Boot, it does not seek to become a general framework for booting any
7 kind of device; instead, it merely attempts to provide a minimal collection of
8 routines for "bare metal" software usage in order to illustrate the
9 initialisation requirements and to make it possible to deploy other software.
10
11 An attempt has been made to also generate payloads for the jz4730-based
12 MiniPC/Mipsbook/Minibook device. This device does not appear to support USB
13 boot mode, and thus any payloads will need to be deployed by other means, such
14 as through the use of SD/MMC media.
15
16 Deployment over USB
17 -------------------
18
19 The payloads can be deployed on the Ben NanoNote using the USB boot mode as
20 described on the Qi-Hardware site:
21
22 http://en.qi-hardware.com/wiki/USB_BOOT_mode
23
24 The provided script can be issued on a USB host machine as follows (given
25 sufficient privileges):
26
27 ./boot_usb
28
29 This employs the xbboot program which is available in the xburst-tools
30 package:
31
32 http://en.qi-hardware.com/wiki/Xburst-tools
33
34 The different MiniPC products do not appear to support USB boot.
35
36 Deployment using microSD/SD/MMC Media
37 -------------------------------------
38
39 The stage 2 payload can be written to a suitable media card as a uImage file
40 which can then be loaded and invoked by a U-Boot bootloader already installed
41 on the Ben NanoNote or MiniPC product.
42
43 Typically, U-Boot on the Ben NanoNote will look for such a file located at
44 /boot/uImage within the first partition of a microSD card. On the MiniPC,
45 U-Boot will look for a file located at /uImage (in other words, a file called
46 uImage in the top-level directory) within the first partition of an SD card.
47
48 Since U-Boot should have initialised the RAM and clocks, the stage 1 payload
49 is superfluous, and only the stage 2 payload is needed in this situation.
50
51 Related U-Boot Resources
52 ------------------------
53
54 For the Ben NanoNote, some resources may only exist in the branch of U-Boot
55 identified as u-boot-2012.10-rc2 when configuring OpenWrt. Others may exist in
56 the principal U-Boot development branch, but differ between that branch and
57 the previous XBurst-supporting branch.
58
59 arch/mips/cpu/xburst/jz4740.c RAM and clock-related initialisation
60 arch/mips/lib/board.c generic board initialisation
61 arch/mips/include/asm/io.h things like readl and writel
62 board/qi/qi_lb60/qi_lb60.c board-specific initialisation
63 common/lcd.c generic LCD initialisation
