Gxlimg is an amlogic s905x boot image creation tools. This has been made by reverse engineering the aml_encrypt_gxl binary used to create boot image as well as the BL2 arm binary that reads FIP header and loads BL3* and u-boot images.
Some reverse engineering notes can be found in reveng directory, please note that because I decompiled aml_encrypt_gxl by hand (not using a tool like IDA), some mistakes could have slept in those notes. The purpose was first to familiarized myself with subject such as ARM assembly and Arm Trust Firmware (ATF).
In order to build this tool just use the following:
$ make
If you want some debug information and print use the following instead:
$ make DEBUG=1
1) Compile u-boot:
Compile mainline u-boot from http://git.denx.de/
$ make CROSS_COMPILE=aarch64-elf- libretech-cc_defconfig $ make CROSS_COMPILE=aarch64-elf- all
Replace aarch64-elf- with the prefix of your aarch64 toolchain. This should produce a u-boot-dtb.bin file.
2) Generate image
Use the image target to generate the build/gxl-boot.bin image.
$ make image UBOOT=<path/to/u-boot-dtb.bin>
In order to create a boot image for s905x board such as lepotato board, you can follow those steps below.
1) Get BL* binaries:
Follow instructions from here https://github.com/BayLibre/u-boot that build vendor u-boot in order to get BL* binaries.
2) Sign BL2:
Use gxlimg as below to sign BL2 binary along with its DDR initialization datas:
$ ./fip/blx_fix.sh fip/gxl/bl2_acs.bin zero_tmp fip/gxl/bl2_zero.bin \ fip/gxl/bl21.bin fip/gxl/bl21_zero.bin bl2_new.bin bl2 $ gxlimg -t bl2 -s bl2_new.bin bl2.bin.enc
3) Encrypt BL3*:
Use the following to encrypt BL3* binary
$ gxlimg -t bl3x -c ./fip/gxl/bl30_new.bin bl30.bin.enc $ gxlimg -t bl3x -c ./fip/gxl/bl31.img bl31.img.enc
4) Compile u-boot:
Compile mainline u-boot from http://git.denx.de/
$ make CROSS_COMPILE=aarch64-elf- libretech-cc_defconfig $ make CROSS_COMPILE=aarch64-elf- all
Replace aarch64-elf- with the prefix of your aarch64 toolchain. This should produce a u-boot-dtb.bin file.
5) Encrypt u-boot:
Encrypt the previously built u-boot image:
$ gxlimg -t bl3x -c u-boot.bin u-boot.bin.enc
6) Create the final boot image:
To create the final image issue the command below:
$ gxlimg -t fip --bl2 ./bl2.bin.enc --bl30 ./bl30.bin.enc \ --bl31 ./bl31.img.enc --bl33 ./u-boot.bin.enc ./gxl-boot.bin
The ROM USB Boot mode on GXL, GXM & AXG uses .usb.bl2 and .usb.tpl files to boot, as used by pyamlboot (https://github.com/superna9999/pyamlboot)
The first binary contains the encrypted BL2 and the second the rest of the gxl-boot.bin
To generate:
$ dd if=gxl-boot.bin of=u-boot.bin.usb.bl2 bs=49152 count=1 $ dd if=gxl-boot.bin of=u-boot.bin.usb.tpl skip=49152 bs=1
Then copy them into files/
1) Prepare the SD card:
First compute how many sectors gxl-boot.bin uses by getting its size and dividing it by 512.
Let's say your gxl-boot.bin is 653312 Bytes thus you need 1276 sectors you can give you a little bit margin and choose a gap of 2048 sectors for your first partion.
Then create the partition:
$ sudo fdisk /dev/mmcpblk0 $ n $ p $ 1 $ 2048 # <- enter the number of sectors previously computed $ # <- take the whole remaining space for the partition $ w
Then create a fs on it:
$ mkfs.ext3 /dev/mmcblk0p1
And copy or install a linux ARM file system.
2) Copy boot image to SD:
The copy image to SD being careful to not erase the first 512 block (holding the MBR partition table)
$ dd if=./gxl-boot.bin of=/dev/mmcblk0 bs=512 seek=1