Trouble loading and running examples on M4 core

[mwilliams]

I'm trying to load and run the "hello world" example on my IMX8MMEVK board by following this page:

https://www.nxp.com/document/guide/get-started-with-the-i-mx-8m-mini-evkb:GS-iMX-8M-Mini-EVK

I have flashed the latest stock Linux BSP to EMMC and I have built my own stock image and flashed the SD card with that.  I can see that the examples are there on the SD card.  I get the following results on the Uboot console:

DDRINFO: start DRAM init
DDRINFO: DRAM rate 3000MTS
DDRINFO:ddrphy calibration done
DDRINFO: ddrmix config done
SEC0:  RNG instantiated
Normal Boot
Trying to boot from MMC1
NOTICE:  BL31: v2.6(release):lf-5.15.32-2.0.0-0-gc6a19b1a3
NOTICE:  BL31: Built : 06:37:22, Jun  7 2022


U-Boot 2022.04-lf_v2022.04+g1c881f4da8 (Jun 07 2022 - 05:16:02 +0000)

CPU:   i.MX8MMQ rev1.0 1800 MHz (running at 1200 MHz)
CPU:   Commercial temperature grade (0C to 95C) at 39C
Reset cause: POR
Model: NXP i.MX8MM EVK board
DRAM:  2 GiB
TCPC:  Vendor ID [0x1fc9], Product ID [0x5110], Addr [I2C1 0x52]
Power supply on USB2
TCPC:  Vendor ID [0x1fc9], Product ID [0x5110], Addr [I2C1 0x50]
Core:  169 devices, 30 uclasses, devicetree: separate
MMC:   FSL_SDHC: 1, FSL_SDHC: 2
Loading Environment from MMC... *** Warning - bad CRC, using default environment

[*]-Video Link 0 (1920 x 1080)
       [0] lcdif@32e00000, video
       [1] mipi_dsi@32e10000, video_bridge
       [2] adv7535@3d, panel
In:    serial
Out:   serial
Err:   serial
SEC0:  RNG instantiated

BuildInfo:
 - ATF c6a19b1

switch to partitions #0, OK
mmc1 is current device
flash target is MMC:1
Net:   eth0: ethernet@30be0000
Fastboot: Normal
Normal Boot
Hit any key to stop autoboot:  0  
u-boot=> fatload mmc 0:1 0x7e0000 imx8mm_m4_TCM_hello_world.bin
Couldn't find partition mmc 0:1
Can't set block device
u-boot=> fatload mmc 1:1 0x7e0000 imx8mm_m4_TCM_hello_world.bin
** Reading file would overwrite reserved memory **
Failed to load 'imx8mm_m4_TCM_hello_world.bin'
u-boot=> fatload mmc 1:1 0x800000 imx8mm_m4_TCM_hello_world.bin
** Reading file would overwrite reserved memory **
Failed to load 'imx8mm_m4_TCM_hello_world.bin'
u-boot=>

What am I missing or doing wrong?

[AldoG · Accepted solution]

Hello,

Please try with the following commands:
> fatload mmc 1:1 0x48000000 imx8mm_m4_TCM_hello_world.bin
> cp.b 0x48000000 0x7e0000 0x20000
> dcache flush
> bootaux 0x7e0000

Best regards,
Aldo.

[mwilliams]

Thanks so much! Now I have to figure out what I did.  If you have any other pearls of wisdom feel free to impart.  Thanks again.

[AldoG]

Hello,

Sorry for not being clear, please see below for a more detailed response:

The command you have used is no longer correct, this is because u-boot from >= L5.4.24  checks if the load address is in a reserved area of memory for u-boot or not.

So now we need to fatload the bin to DDR (0x48000000) by using the following command:
> fatload mmc 1:1 0x48000000 imx8mm_m4_TCM_hello_world.bin

Next will be copying the binary from that location to TCM (0x7e0000)
> cp.b 0x48000000 0x7e0000 0x20000

Finally we flush dcache and boot the auxiliary core (Cortex-M4)
> dcache flush
> bootaux 0x7e0000

Best regards,
Aldo.