From: Priit Laes priit.laes@paf.com
Signed-off-by: Priit Laes plaes@plaes.org --- board/sunxi/README.fastboot | 98 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 98 insertions(+) create mode 100644 board/sunxi/README.fastboot
diff --git a/board/sunxi/README.fastboot b/board/sunxi/README.fastboot new file mode 100644 index 0000000..470fa6f --- /dev/null +++ b/board/sunxi/README.fastboot @@ -0,0 +1,98 @@ +Using fastboot on sunxi devices +=============================== + +Fastboot is a diagnostic protocol, primarily used to modify the +filesystems on the flash device via USB or UDP. It requires that +the device is started in a boot loader or Seconday Boot Loader mode. + +This document currently walks through an installation with a device +with eMMC storage. + +Prerequisites +------------- + +* fastboot binaries installed on client machine +* sunxi-tools installed on client machine (optional) +* u-boot tools (mkimage) +* u-boot binaries for the target sunxi device +* filesystem images + * root file system containing operating system + * vfat file system +* Sunxi device connected to client via OTG port + +Getting your device into Fastboot mode +-------------------------------------- + +To enter into fastboot mode, execute the `fastboot` command in +U-Boot: + +$ fastboot usb 0 + +On the client machine, you can check whether the device is visible +using the `fastboot devices` command. And for fun, you can also +fetch the bootloader version using the fastboot protocol: + +$ fastboot devices +1234567890abcdef fastboot +$ fastboot getvar bootloader-version +bootloader-version: U-Boot 2018.11-rc2-00033-ge3beca3a2f +finished. total time: 0.000s + +Preparing the device for flashing +--------------------------------- + +Now that the device is in the fastboot mode, we can continue with +creating the partitions on the device. By default, u-boot for sunxi +defines following partitions: + +* loader1 - partition for secondary program loader +* loader2 - partition for u-boot +* esp - EFI system partition, also used for u-boot to look up boot.scr +* system - Root partition for system + +These partitions have also assigned GUID's according to Discoverable +Partitions Specification [1], to enable automatic discovery of partitions +and their mountpoints. + +You can start by formatting the internal storage by executing the +`fastboot oem format` command from client: + +$ fastboot oem format + +This equivalent to running the `gpt write mmc 1 $partitions` from u-boot. + +[1] https://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/ + +Flashing the device +------------------- + +Now that we have the partitions created, all that is left for us +is to flash the data. + +`loader1` is used for storing the Seconday Program Loader, in our +case, it is the `spl/sunxi-spl.bin` in the u-boot directory: + +$ fastboot flash loader1 spl/sunxi-spl.bin + +`loader2` is for storing the u-boot binary. `u-boot.img` in the +u-boot source directory: + +$ fastboot flash loader2 u-boot.img + +`esp` partition (EFI System Partition) can be kept empty, although +if it is VFAT partition, u-boot automatically looks up the `boot.scr` +file for device-specific configuration. (You can create empty vfat +partition by `fallocate -l 32M esp.img && mkfs.vfat esp.img`) + +$ fastboot flash esp esp.img + +`system` partition is where the operating system resides. Creating +that is left as an exercise to the reader. + +$ fastboot flash system system.img + +Now, if everything has been properly set up (aka proper kernel +with machine-specific dtb installed on system.img, and boot.scr +on esp partition), you can reboot the machine: + +$ fastboot reboot