# GX BootROM notes

Sample bootROM UART log of a successful boot on Amlogic S805Y:

`GXL:BL1:9ac50e:bb16dc;FEAT:BDFD71BC:0;POC:3;RCY:0;EMMC:0;READ:0;0.0;0.0;CHK:0;`

### Status messages

* `GXL:BL1:9ac50e:bb16dc`: Indicates SoC generation, git commit hash (?)
* `FEAT`: Dump of `SECUREBOOT_FLAG` (`0xc8100228`):
* `POC`: POC pin
* `RCY`: If HDMI boot dongle is plugged in, this is `1`, else `0`

### Boot device status

* `EMMC`/`SD`/`SPI`/`USB`/`NAND`: Supported boot devices
* `CHK`: Image/Payload checks
    * `0`: Success, no error
    * `A7`: Wrong magic (!= `@AML`) or version number
    * `C7`: Wrong header size or digest offset
    * `CF`: Payload size or offset too big

### EFUSE/OTP

Where many settings are set, e.g. regarding SecureBoot.  A copy of it is 
available at `0xd9013c00` (in AHB SRAM).

The AES key and IV are located at `0xd9013c50` and `0xd9013c70` respectively.
On a secureboot-enabled device, they can be dumped easily using 
[amlogic-usbdl](https://fredericb.info/2021/02/amlogic-usbdl-unsigned-code-loader-for-amlogic-bootrom.html).

[Will do more research later]