| parent | /Hardware/ |
|---|---|
| SPDX-License-Identifier | CC-BY-SA-4.0 |
| SPDX-FileCopyrightText | 2020 seL4 Project a Series of LF Projects, LLC. |
The ARM platform has many ways to boot into an operating system. Typically there is some low-level ROM code (very specific to each device) that turns on RAM, and turns on enough clocks to be able to load a second-stage bootloader which does the work. Some do this in several stages, to enable Trust Zone, HYP-mode etc.
The main bootloaders after the ROM are U-Boot, UEFI, Loki (for Samsung devices) and simpleboot. Most of these provide Fastboot over USB to allow software loading.
On UEFI for arm: http://blog.hansenpartnership.com/efitools-for-arm-released/ On U-Boot for arm: http://www.denx.de/wiki/U-Boot
Load from U-Boot, from SD card or flash, or using Fastboot or TFTP. Most applications have two parts: treat the "kernel" part as a kernel, and the "application" part like an initial root disk. If there is only one part to an image (e.g., seL4test for some platforms) treat it like a kernel.
Detailed instructions differ from board to board. See the Supported Platforms page for links to board-specific instructions.
Most ARM platforms other than the Beagle Boards that seL4 can use support booting via Fastboot.
To boot via Fastboot, you need to convert the image file produced by the seL4 build system into a U-Boot image.
mkimage -A arm -a 0x48000000 -e 0x48000000 -C none -A arm -T kernel -O qnx -d INPUT_FILE OUTPUT_FILEThe reason we choose -O qnx is because we exploit the fact that, like seL4,
QNX expects to be ELF-loaded. The alternative is to convert our ELF file into a
binary file using objcopy. The address to use varies from board to board.
Unless you change the load address, use these:
| Platform | Address |
|---|---|
| Arndale, Odroid-X, Odroid-XU | 0x48000000 |
| Sabre Lite | 0x30000000 |
| Panda, Panda ES | 0x80000000 |
When you have your image, put the board into Fastboot mode (interrupt U-Boot, and type "fastboot"), then do:
fastboot boot OUTPUT_FILE
Pull out the SD card from your board, and put it into an SD card reader attached to your build host. Mount the (MS-DOS) filesystem on the first partition on the SD card and copy your image to it. Unmount the filesystem, and put the card back into your board. Reset the board (by power cycling, or pressing the reset button). To run the image:
mmc init
mmcinfo
fatload mmc 0 ${loadaddr} sel4test-image-arm
bootelf ${loadaddr}
You can use
fatls mmc 0
to see what is there. Most U-Boot implementations define a suitable loadaddr
in their environment.
Setting up a DHCP and TFTP server are out of scope for this document. Once you have done that, however, and installed a TFTP-enabled U-Boot on your board if it doesn't already have one.
You can then power up the device and stop U-Boot's auto boot feature if enabled by pressing a key, and do:
dhcp file address
bootelf address