how to use Buildroot and latest Kernel, TF-A and U-Boot (ST GitHub)?

[Michele1]

I'm a newbie with embedded topics, for educational purposes I'm trying to set up my ST32MP157C-DK2 using Buildroot.

Using menuconfig I pointed Kernel, TF-A and U-boot to the latest label releases of ST forked repos. But it did not work because it asked for FIP image.

I enabled FIP image using menuconfig, but building fails. After investigating a bit, I realized Buildroot is missing a value for the variable BL33_CFG, which from some documentation I understand it should be set to the U-Boot dtb.

Looking at the code and makefiles I couldn’t find a properly supported pattern for this, so I have made few changes: Buildroot to copy u-boot.dtb to the output folder, and set from menuconfig an additional variable for ARM_TRUSTED_FIRMARE:

BL33_CFG=$(BINARIES_DIR)/u-boot.dtb.

and also defined BR2_TARGET_ARM_TRUSTED_FIRMWARE_UBOOT_BL33_IMAGE=�?u-boot-nodtb.bin�?

Now building succeed without issues apparently.

The next step would be to flash using STM32CubeProgrammer, I use this tsv file:

———–
 
 #Opt	Id	Name	Type	IP	Offset	Binary
 
 –	0x01	fsbl1-boot	Binary	none	0x0	tf-a-stm32mp157c-dk2.stm32
 
 –	0x03	fip-boot	Binary	none	0x0	fip.bin
 
 P	0x04	fsbl1	Binary	mmc0	0x00004400	tf-a-stm32mp157c-dk2.stm32
 
 P	0x05	fsbl2	Binary	mmc0	0x00044400	tf-a-stm32mp157c-dk2.stm32
 
 PD	0x06	fip	Binary	mmc0	0x00084400	fip.bin
 
 P	0x10	rootfs	System	mmc0	0x00484400	rootfs.ext2
 
 ———–

but when I boot the board, it hangs at Starting Kernel...

does anyone has any suggestion that helps to spot where the issue is?

NOTICE:  CPU: STM32MP157CAC Rev.B
NOTICE:  Model: STMicroelectronics STM32MP157C-DK2 Discovery Board
NOTICE:  Board: MB1272 Var2.0 Rev.C-01
NOTICE:  BL2: v2.4-r1.0(release):2021.02-909-g60859ea55a-dirty
NOTICE:  BL2: Built : 22:26:49, May  3 2021
NOTICE:  BL2: Booting BL32
NOTICE:  SP_MIN: v2.4-r1.0(release):2021.02-909-g60859ea55a-dirty
NOTICE:  SP_MIN: Built : 22:26:49, May  3 2021
 
 
U-Boot 2020.10-stm32mp-r1 (May 03 2021 - 22:26:28 +0300)
 
CPU: STM32MP157CAC Rev.B
Model: STMicroelectronics STM32MP157C-DK2 Discovery Board
Board: stm32mp1 in trusted mode (st,stm32mp157c-dk2)
Board: MB1272 Var2.0 Rev.C-01
DRAM:  512 MiB
Clocks:
- MPU : 650 MHz
- MCU : 208.878 MHz
- AXI : 266.500 MHz
- PER : 24 MHz
- DDR : 533 MHz
WDT:   Started with servicing (32s timeout)
NAND:  0 MiB
MMC:   STM32 SD/MMC: 0, STM32 SD/MMC: 1
Loading Environment from MMC... OK
In:    serial
Out:   serial
Err:   serial
Net:   eth0: ethernet@5800a000
Hit any key to stop autoboot:  0 
Boot over mmc0!
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:4...
Found /boot/extlinux/extlinux.conf
Retrieving file: /boot/extlinux/extlinux.conf
131 bytes read in 41 ms (2.9 KiB/s)
1:      stm32mp157c-dk2-buildroot
Retrieving file: /boot/zImage
4347640 bytes read in 225 ms (18.4 MiB/s)
append: root=/dev/mmcblk0p4 rootwait
Retrieving file: /boot/stm32mp157c-dk2.dtb
116117 bytes read in 46 ms (2.4 MiB/s)
Kernel image @ 0xc2000000 [ 0x000000 - 0x4256f8 ]
## Flattened Device Tree blob at c4000000
   Booting using the fdt blob at 0xc4000000
   Loading Device Tree to cffe0000, end cffff594 ... OK
 
Starting kernel ...

[Olivier GALLIEN]

Hi @Michele​ ,

First, be aware that ST does not deliver, hence, support buildroot as build system.

You should rather contact some partners or community ( eg Bootlin) to get some support.

Anyway when facing issue at early stage of kernel start it usually helps to set the early printk

see https://wiki.st.com/stm32mpu/wiki/Dmesg_and_Linux_kernel_log#earlyprintk

Hope it help,

Olivier

[Michele1 · Accepted solution]

Hi @Community member​ ,

yes indeed I did not pretend heavy support from ST about Buildroot, nevertheless I decided to post here in the Community, in case someone else would stumble in the same case.

And your suggestion pointed me to the right direction, thanks!

After enabling early printk I could see that the Kernel log was quite different from the one I get when I use the official ST Developer and Distribution packages. After updating the Kernel config that is by default shipped with Buildroot with the one from the Developer package then everything started working as expected.

Thanks again!

Michele