Before we can build a complete coreboot firmware image for the H4+, we need to read the manufacturer's firmware to extract the relevant flash regions.
The flash chip does not have a connector to access the flash chip. However, due to the SOI8 package format, the pinout is easily accessible using the appropriate test clip. The only thing to note is the polarity of the connection. Pin 1 (CS) is marked with a dot on the chip and a red wire on the test clip, which must match to avoid bricking the board. The picture below shows the primary chip we will use to flash coreboot.
To use the picoprog to read the NOR flash containing the firmware, we need to use a programmer software that supports the Serprog Protocol. For this we recommend the use of either flashrom or flashprog. For detailed instructions on how to read the flash chip, please refer to the picoprog README.md.
Before starting the configuration, extract the relevant Flash regions using ifdtool. The extracted soc information will be saved to your local working directory.
Intel FDT
The Intel Flash Descriptor (IFD) defines offsets and sizes of various regions of the flash. It is used to define coreboots flashmap, which describes partitions on the flash chip. For further details refer to the [official coreboot documentation](https://review.coreboot.org/plugins/gitiles/coreboot/+/0cd098e4e41d6bb3b27327d4a6526bd7004bfc77/Documentation/ifdtool/layout.md)./path/to/ifdtool -x /path/to/ODROID-H4-PLUS-1.rom
The command above should dump the neccessary binaries into your current directory. The files will be called something like "flashregion__.bin". Now we need to tell coreboot where the binaries are.
If you have built another mainboard before (e.g. QEMU), you should run make distclean before configuring the new target.
For configuration start make menuconfig, select "Hardkernel" as the mainboard vendor and include the IFD (Flash descriptor) and ME (Management Engine) flash region via the config menu by their file path.
IFD make menuconfig path: "Chipset/Add Intel descriptor.bin file".
After enabling the option a new option should appear which needs a file path to the "flashregion_0_flashdescripttor.bin" file
ME make menuconfig path: "Chipset/Add Intel ME/TXE firmware"
After enabling the option a new option should appear which needs a file path to the "flashregion_2_intel_me.bin" file
In the menuconfig choose: Payload/Payload to add/edk2 Payload
In the menuconfig choose: Payload/Tianocore's EDK 2 payload/edk2 Payload
In the menuconfig Insert edk2-stable202408 into: Payload/Payload to add/Insert a commits SHA-1 or a branch name
All other default configurations are sufficient to boot the board.
./flashprog -p serprog:dev=/dev/ttyACM2 -w PATH/TO/COREBOOT/build/coreboot.rom
Now disconnect the flash clip.
The GPIO pin assignment of our target hardware can be found here: ODROID Wiki: H4 I/O Expansion GPIO MAP
Use a tree jumper cable to connect GND and RX to TX and vice versa.
Depending on the configured log level, the coreboot console provides substitute information during the boot process. Therefore, you should make sure that the UART is set up properly. The picoprog provides an additional interface to connect to the UART. Use the software of your choice to connect to it. e.g:
<tio/picocom> -b 115200 /dev/serial/by-id/usb-9elements_Picoprog_OSFC2024-if02
or
cu -l /dev/serial/by-id/usb-9elements_Picoprog_OSFC2024-if02 -s 115200
We have live ubuntu Linux system with the serial console enabled by default on USB sticks. To test if the UART communication is working, you should first boot the system and check. You should see coreboot logs as well as Linux ubuntu logs and a console to login into.
If you have the USB stick attached to the odroid, you should see a ubuntu live iso image booting up. Congratulations you have successfully compiled, flashed and booted Firmware.
Now you can either go free style or try to solve some of the challenges that we have prepared. You could for example poke around with the code and the configuration options. Just be careful with the internal GPIO related configuration as a misconfiguration could potentially brick the hardware. If you run out of ideas, just ask the staff. They might know something you can try out.
TODO