README.txt
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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.