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 Building a Payload
17 ------------------
18
19 To build the payload for the Ben NanoNote, just run make:
20
21 make
22
23 To build the payload for the MiniPC, define MINIPC in the invocation:
24
25 make MINIPC=yes
26
27 Make sure to clean if switching between these targets:
28
29 make clean
30
31 Deployment over USB
32 -------------------
33
34 The payloads can be deployed on the Ben NanoNote using the USB boot mode as
35 described on the Qi-Hardware site:
36
37 http://en.qi-hardware.com/wiki/USB_BOOT_mode
38
39 The provided script can be issued on a USB host machine as follows (given
40 sufficient privileges):
41
42 ./boot_usb
43
44 This employs the xbboot program which is available in the xburst-tools
45 package:
46
47 http://en.qi-hardware.com/wiki/Xburst-tools
48
49 The different MiniPC products do not appear to support USB boot.
50
51 Deployment using microSD/SD/MMC Media
52 -------------------------------------
53
54 The stage 2 payload can be written to a suitable media card as a uImage file
55 which can then be loaded and invoked by a U-Boot bootloader already installed
56 on the Ben NanoNote or MiniPC product.
57
58 Typically, U-Boot on the Ben NanoNote will look for such a file located at
59 /boot/uImage within the first partition of a microSD card. On the MiniPC,
60 U-Boot will look for a file located at /uImage (in other words, a file called
61 uImage in the top-level directory) within the first partition of an SD card.
62
63 Since U-Boot should have initialised the RAM and clocks, the stage 1 payload
64 is superfluous, and only the stage 2 payload is needed in this situation.
65
66 Related U-Boot Resources
67 ------------------------
68
69 For the Ben NanoNote, some resources may only exist in the branch of U-Boot
70 identified as u-boot-2012.10-rc2 when configuring OpenWrt. Others may exist in
71 the principal U-Boot development branch, but differ between that branch and
72 the previous XBurst-supporting branch.
73
74 arch/mips/cpu/xburst/jz4740.c RAM and clock-related initialisation
75 arch/mips/lib/board.c generic board initialisation
76 arch/mips/include/asm/io.h things like readl and writel
77 board/qi/qi_lb60/qi_lb60.c board-specific initialisation
78 common/lcd.c generic LCD initialisation
