Bootelf on IMX6.UL

[jiangshan_wei]

hi，

    Now I am using I.MX6UL development board named "i.MX6UltraLite Evaluation Kit (EVK)" . what i did is:

1: Install SDK_2.2_MCIM6UL on my PC.

2: Build one standalone elf executable file with demo IAR project in SDK folder “C:\nxp\SDK_2.2_MCIM6UL\boards\evkmcimx6ul\driver_examples\gpt\capture”. 

2: press any key to stop auto-uboot, with uboot version  "uboot-imx-imx_v2016.03_4.1.15_2.0.0_ga".

3: load elf file via command bootelf

=> fatload mmc 1:1 0x80800000 gpt_capture.out
reading gpt_capture.out
217948 bytes read in 35 ms (5.9 MiB/s)

4：Boot elf from memory. 
=> bootelf 0x80800000

 And my question is

  1: Any idea why demo binary file execution is stuck? Assume application timer should start ticking.

  2: How to disable interrupts initialized by U-boot? I mean how to diasble intterupts before bootelf command.

Thanks for the help in advance!

[Pavel]

There are no recommendations from u-boot developers (www.denx.de) about similar u-boot changing.

It looks like that the following command sequence is needed.

1. Disable all interrupts
2. Replace exception handlers.
3. Enable interrupts.

Have a great day,
Pavel Chubakov

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[Pavel · Accepted solution]

Look at the following page. This page contains "Timer demo" example for using a CPM interrupt handler with the U-Boot code.

See also the following pages:

http://variwiki.com/index.php?title=Yocto_Customizing_U-Boot

https://boundarydevices.com/customizing-u-boot-on-i-mx/

https://www.quora.com/How-do-I-customize-the-U-boot-bootloader

https://community.nxp.com/thread/445938

http://xillybus.com/tutorials/uboot-hacking-howto-1

https://rocketboards.org/foswiki/Documentation/PreloaderUbootCustomization131

See the following document about u-boot customizing under Yocto:

https://www.imx6rex.com/open-rex/software/how-to-edit-customize-and-test-the-uboot-kernel-source-cod...

Have a great day,
Pavel Chubakov

[jiangshan_wei]

Appreciate the links, it helpful for me. May I have one more asking. Could you share the guide/link about relocating vector table for RTOS in DDR by booting with uBoot.

[jiangshan_wei]

Let me clarify myself, I am looking for the method to replace Uboot exception handler with my ROTS exception handlers .Thanks

[Pavel]

The i.MX6 u-boot is not operating system.

Find the "Standalone HOWTO:" in u-boot README file.

This file is available using the following link:

https://github.com/u-boot/u-boot/blob/master/README

Have a great day,
TIC

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[jiangshan_wei]

hi Pavel, 

   thanks for the help, checked. Booting standalone application are directly runnable in the environment
provided by U-Boot.  But now I also need to  install my own set of exception handlers, device drivers, set up the MMU, etc... like linux OS， and i also need the leverage HAB feature on I.MX6UL processor.

   Could you give me some advice about below items: 

   1: Is customizing U-boot the fastest approach？Any other better approach for that?

   2: If customizing U-boot is the fastest approach, could you help to share some guide/doc about that？

thanks

[yali_zhang]

Can you use the bootelf to start an application? Could you share your findings?

[jiangshan_wei]

One more input, after bootelf is called by Uboot, then connect IAR and start debugging, there is a warning in debug log "Tue Mar 12, 2019 09:22:19: The stack pointer for stack 'IRQ_STACK' (currently 0x00000013) is outside the stack range (0x800111C0 to 0x800112C0) "