README.txt

The kit i.MX93 Evaluation Kit has a pre-installed Linux image which contains u-boot and the i.MX93 reference Linux installation.

NuttX may work as the bootloader, replacing u-boot completely. Currently it doesn't initialize the DDR memory yet. In other words, DDR training is still missing.

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How to run nuttx on i.MX93 Evaluation Kit.

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Below is a set of instructions on how to run NuttX on the i.MX93 EVK, on top of the u-boot. Also, instructions on running NuttX as the bootloader will follow.

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Pre-requisites

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• imx93_ca55.JLinkScript which is a custom file, put it wherever you want

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U-Boot configuration

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Two things need to be configured on u-boot before NuttX can be loaded:

• u-boot data cache must be turned off
• u-boot must stop to the u-boot console, i.e. the Linux payload must not be loaded

Manual option:

1. Disable u-boot autostart (needs to be done only once):

   Hit any key to stop autoboot: 0 u-boot=> setenv bootdelay -1 u-boot=> saveenv Saving Environment to MMC... Writing to MMC(0)... OK u-boot=> reset

2. On every boot, the data cache must be disabled for options 2 and 3 to work

   u-boot=> dcache off

Automated option:

1. Replace the default bootcmd to disable dcache automatically:

   u-boot=> setenv bootdelay 0 u-boot=> setenv bootcmd dcache off u-boot=> saveenv Saving Environment to MMC... Writing to MMC(0)... OK u-boot=> reset

To restore the default bootcmd which starts Linux automatically:

u-boot=> setenv bootcmd run distro_bootcmd;run bsp_bootcmd
u-boot=> saveenv
Saving Environment to MMC... Writing to MMC(0)... OK
u-boot=> reset

The default bootcmd is:

u-boot=> env print bootcmd bootcmd=run distro_bootcmd;run bsp_bootcmd

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Loading and running the NuttX image

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You have four options:

1 - Load via u-boot from SD-card 2 - Load via gdb 3 - Load via JLink 4 - Run from SD-card, without u-boot 5 - Kernel build, via AHAB boot

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Option 1: load via u-boot from SD-card:

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1. Build nuttx, and move nuttx.bin to SD-card

2. Load from SD-card and start nuttx payload

   u-boot=> dcache off; fatload mmc 1 0x80000000 nuttx.bin; go 0x80000000

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Option 2: start via gdb:

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1. Start JLinkGDBServer

   JLinkGDBServer -device CORTEX-A55 -JLinkScriptFile <path_to>/imx93_ca55.JLinkScript

2. Start gdb

   $ aarch64-none-elf-gdb

2.1 Attach and load nuttx

(gdb) target remote localhost:2331
(gdb) set mem inaccessible-by-default off
(gdb) load <path_to>/nuttx
(gdb) monitor go

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Option 3: load with JLink:

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1. Start JLink

   $ JLinkExe -device CORTEX-A55 -if JTAG -jtagconf -1,-1 -speed 4000 -JLinkScriptFile <path_to>/imx93_ca55.JLinkScript

1.1 Add -AutoConnect 1 to connect automatically

$ JLinkExe -device CORTEX-A55 -if JTAG -jtagconf -1,-1 -speed 4000 -JLinkScriptFile <path_to>/imx93_ca55.JLinkScript -AutoConnect 1

2. Connect JLink

2.1 Connect to the debugger

Type "connect" to establish a target connection, '?' for help
J-Link>connect

You should now have a JLink prompt.

Cortex-A55 identified.
J-Link>

3. Load nuttx. Note that JLink expects the .elf extension, the default build output of nuttx is just "nuttx" without the extension, so it must be added to the file...

   J-Link>LoadFile <path_to>/nuttx.elf

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Option 4: Run from SD-card, without u-boot

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1. Make sure CONFIG_IMX9_BOOTLOADER is set and system is configured properly for bootloader operation:

tools/configure.sh imx93-evk:bootloader

2. The build outputs a file "imx9-sdimage.img". This image also contains the Ahab container. It's required to grant Trusted Resource Domain Controller (TRDC) permissions. Flash it to an SD-card, where sdX may be sda or something else; verify the block device name properly (eg. /dev/sda, /dev/sdb etc):

sudo dd if=imx9-sdimage.img of=/dev/sdX bs=1k && sync

3. Insert the SD-card into the imx93-evk, make sure BMODE switch is [1,2,3,4] = [Off, On, Off, Off] so that it boots from the SD-card.

This should boot into NuttShell in EL3 level.

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Option 5: Kernel build, via AHAB boot

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1. Follow the instructions at: https://spsdk.readthedocs.io/en/latest/examples/ahab/imx93/imx93\_ahab\_uboot.html to create an eMMC-bootable image (latest version of instructions tested is v2.6.1). We will be replacing the u-boot binary in step 2.3 with NuttX.

2. Clone both NuttX and NuttX-Apps in same level directories nuttx and apps respectively.

3. Configure and build NuttX:

cd nuttx tools/configure.sh imx93-evk:knsh make make export

4. Build NuttX apps and prepare the /bin ROMFS image:

pushd ../apps tools/mkimport.sh -z -x ../nuttx/nuttx-export-*.tar.gz make import tools/mkromfsimg.sh mv boot_romfsimg.h ../nuttx/boards/arm64/imx9/imx93-evk/include/bin_romfsimg.h popd

5. Re-build NuttX embedding the generated /bin ROMFS image:

make clean clean_context make

6. Replace the value of the u-boot: entry in workspace/ahab_template.yaml created in step 1 above with the path to nuttx.bin.