Boot from Flash confusion

[brownd1970]

I'm going round in circles with how to move my development into  production with a simple process. I'm using the iMXRT1062 with IS25WP QSPI flash memory.

The BOOT_MODE[1] pin is pulled high, BOOT_MODE[0] pin is pulled low.

All BOOT_CONFIG pins are pulled low.

I have code built using Zephyr that runs without issue and I have used MCUBoot to create the bootloader with signed protection for loading the image.

If I load my combined HEX file into clean board using J-Link then nothing happens, but if I then connect using NXP-MCUBootUtility over UART then it jumps into life after connection - and then forever after it runs fine - but I've not deliberately changed any fuse settings.

Or, if I use the Secure Provisioning Tool to create the image from my bootloader HEX and my signed image HEX - it will then load incredibly slowly over UART.

My question is why can't I load my combined HEX file over J-Link and then it start running? My BOOT_MODE pins are set to run internally and my BOOT_CONFIG pins tell it to run from FLASH - don't they? I need to make it simple for production, and the simplest is to load a HEX file into a programmer.

Thanks

[brownd1970]

Yes, I'm starting to think that's exactly what the problem is. But how can I add that without having to use those tools?

As I said previously the SPT is incredibly slow over UART. Or can I use the image created from that and load it using SWD interface as the JLink does?

[Omar_Anguiano]

Yes, it is an option to use the generated image from SPT and load it through the debugger. 

BR,
Omar

[brownd1970]

I've used SPT to take my MCUboot+MainApp merged hex file and created an binary image on the "Build Image" tab. If I use the "Write Image" tab using UART interface then it loads in ~10mins and then works correctly.
But if I import that binary file into J-Flash then program using SWD then it loads in seconds but doesn't then run afterwards.

Loading the original hex file into J-Flash shows code has been added between 0x60000000 and 0x60020000 but then code afterwards is also different... I can also see this on the original MainApp binary image before it was converted to hex and before it was merged with MCUBoot.

[Omar_Anguiano · Accepted solution]

When you use the Secure Provisioning Tool (SPT) to build the image, it prepends the FCB and IVT to the binary so that the ROM bootloader can correctly initialize the QSPI flash and jump to your bootloader. This is why it works after UART flashing — the ROM sees the FCB and knows how to boot.

However, when you flash the same binary via J-Flash, it’s likely being written to the wrong address or without proper alignment, so the ROM bootloader doesn’t find the FCB at the expected location (0x60000000).

To make your production process work with J-Flash (SWD), you need to ensure:
The binary includes the FCB and IVT at the correct offset.
The binary is flashed to address 0x60000000, which is the start of the external QSPI flash.
The image layout is correct:

• 0x60000000: FCB
• 0x60001000: IVT + Bootloader
• 0x60002000 or later: Signed application image

On your image merged, you can make it to start at address 0x0 just like the SPT image, and when loading it on SWD, load it from 0x60000000.

BR,
Omar

[Sunil_13]

Hi @Omar_Anguiano ,

We are working with the i.MX8M Plus EVK, which has 32 MB QSPI flash.
Our goal is to boot U-Boot, Linux kernel, device tree, and initramfs (rootfs.img ) entirely from QSPI flash.

We are able to successfully boot:

U-Boot (from flash.bin)

Linux kernel (Image.gz)

Device Tree (imx8mp-evk.dtb)

However, we are facing issues when loading and using the initramfs/rootfs image from QSPI flash. The kernel starts successfully, but the kernel hangs at Waiting for removable media.... see the below log attached.

-----Flash Layout and Image Sizes----------------

QSPI flash size: 32 MB

flash.bin (U-Boot + SPL) ~2.3 MB
Image.gz (Kernel) ~13.5 MB
imx8mp-evk.dtb ~86 KB
rootfs.img ~12.6 MB

----QSPI Offset Layout----------
flash.bin @ 0x00000000
Image.gz @ 0x00240000
imx8mp-evk.dtb @ 0x01000000
rootfs.img @ 0x01080000

------Programming files into QSPI (from SD card)---------
sf probe 0
sf erase 0x0 0x2000000

fatload mmc 1 ${loadaddr} flash.bin
sf write ${loadaddr} 0x0 ${filesize}

fatload mmc 1 ${loadaddr} Image.gz
sf write ${loadaddr} 0x240000 ${filesize}

fatload mmc 1 ${loadaddr} imx8mp-evk.dtb
sf write ${loadaddr} 0x1000000 ${filesize}

fatload mmc 1 ${loadaddr} rootfs.img # initramfs (cpio.gz)
sf write ${loadaddr} 0x1080000 ${filesize}

------After flashing,power-cycle the board--------------

After boot from u-boot,setting the env variables for Linux kernel (Image.gz),Device Tree (imx8mp-evk.dtb),rootfs.img.

sf probe 0
setenv loadaddr 0x40480000 // kernel
setenv fdt_addr 0x43000000 //dtb
setenv initrd_addr 0x43800000 //rootfs
setenv kernel_comp_addr_r 0x50000000
setenv kernel_comp_size 0x04000000

sf read ${loadaddr} 0x240000 0xCD3CE2

sf read ${fdt_addr} 0x1000000 0x14360

sf read ${initrd_addr} 0x1080000 0xC04DB0

setenv bootargs "console=ttymxc1,115200 root=/dev/ram0 rw"

setenv bootcmd 'sf probe 0; sf read ${loadaddr} 0x240000 0xCD3CE2; sf read ${fdt_addr} 0x1000000 0x14360; sf read ${initrd_addr} 0x1080000 0xC04DB0; booti ${loadaddr} ${initrd_addr} ${fdt_addr}'

saveenv

-----------------------Question 1------------------------------------
1.With SD card Wic file working fine with partitions (Boot/Root).
2.We genarated Two yocto images
==> 1.bitbake core-image-minimal-initramfs (generated initramfs.cpio.gz) this cpio.gx converted into rootfs.img by using this cmd mkimage -A arm -O linux -T ramdisk -d <gzipped_rootfs> <Ramdisk_name> (from linux user guide)
==>2.Also generated tiny rootfs from yocto generated using bitbake core-image-tiny. core-image-tiny-imx8mp-evk.tar.zst this tar extracted into EXT4 partition in SD card succussfully loading tiny rootfs .
3.But as said in 2nd point rootfs.img also put into EXT4 root partition in SD card but not loading the rootfs.

-----------------------Question 2------------------------------------
1.Is this the correct approach to boot an initramfs (rootfs.img) directly from QSPI on i.MX8M Plus EVK?

-----------------------Question 3------------------------------------
3.Is there any recommended NXP reference image for booting kernel and initramfs entirely from QSPI on i.MX8MP(Linux kernel (Image.gz),Device Tree (imx8mp-evk.dtb),rootfs.img) ?

[brownd1970]

OK, so my problem is now narrowed down to I need to understand how to use the Secure Provisioning Tool. Thanks

[Omar_Anguiano]

It is possible that your image does not have the necessary headers, the FCB is needed so the ROM bootloader knows how to communicate with the flash. MCUBootUtility and SPT add these headers.

BR,
Omar