Load signed u-boot on secure board through JTAG

[mohamed-ali_fod]

Hi,

I want to load signed u-boot using JTAG on imx6 processor. The same below steps work fine after DDR initialization but, the u-boot run and I can get console only on non secure board, but it doesn't run on secure board (SECURE_CONFIG bit enabled). For information I already check that the signed u-boot works fine on another secured board.

loadbin ./u-boot-spinor-signed.imx.bin 0x177ff400
SetPC 0x17800000
g

Downloading file [./u-boot-spinor-2020.04-r1.imx.bin]...
O.K.

VerifyBin ./u-boot-spinor-signed.imx.bin 0x177ff400
Loading binary file ./u-boot-spinor-signed.imx.bin
Reading 689472 bytes data from target memory @ 0x177FF400.
Verify successful.

As mentioned above the load works well on secure and non secure board but the loaded u-boot works only on non secure board.

Could you please help? Are the 0x17800000 or 0x177FF400 addresses still valid in case of secure board?

Best regards,

Mohamed Ali

[Dhruvit]

Hi @mohamed-ali_fod,

I hope you are doing well.

->You need some u-boot executable that's been built to work on the board.

-> Please check the below documents for your reference.

http://imx6dev.blogspot.ru/2014/07/inexpensive-jtag-on-imx6-solo-u-boot.html

http://www.denx.de/wiki/view/DULG/DebuggingUBoot

https://boundarydevices.com/jtag-adaptor-for-i-mx6-boards/

Thanks & Regards,
Dhruvit Vasavada

[mohamed-ali_fod]

Hi Dhruvit,

Of course I have functional u-boot that works for this board , it works if the u-boot is flashed in the flash memory. Also the same u-boot works fine for non secured board through jtag as I mentioned in my previous email (u-boot-spinor-signed.imx.bin). But my question why this u-boot doesn't work through jtag in secured board (secure_config fuse enabled), what could be the difference vs non secure board.

I hope the question is clear.

Thank you in advance,

Mohamed Ali

[Dhruvit]

Hi @mohamed-ali_fod,

I hope you are doing well.

->Can you let me know if secure JTAG is enabled or not?
->Please verify whether the CSF file had the correct UID.

->Please refer to 5.2.13.1  Unlock Examples in Code-Signing Tool User’s Guide
https://www.nxp.com/webapp/Download?colCode=IMX_CST_TOOL_NEW

Thanks & Regards,

Dhruvit Vasavada

[mohamed-ali_fod]

Hi @Dhruvit, 

The secure JTAG is not enabled I enabled only secure_config fuse.

Is it mandatory to add UID in CSF to load signed u-boot through jtag?

Please note that my signed u-boot is working well on my board if the board boot from memory flash, my problem is to boot the board using signed u-boot loaded through jtag.

Best regards,

Mohamed Ali

[Dhruvit]

Hi @mohamed-ali_fod,

I hope you are doing well.

One needs to enable Secure JTAG mode on a closed device.

It limits the JTAG access by using a challenge/response-based authentication mechanism.

Please refer to Secure Debug in i.MX 6/7/8M Family of Applications Processors for more information.

Thanks & Regards,
Dhruvit Vasavada

[nick_king]

"One needs to enable Secure JTAG mode on a closed device." Is this a recommendation, or a requirement such that the JTAG Enabled mode will not work once the HAB fuse has been blown?
Thanks, Nick

[nick_king]

Further to the above, if it is a requirement and I haven't blown any of the SJC_RESP fuses, is there a default value such that a Lauterbach can access with an appropriate response - i.e. all zeroes or all ones?
And, although slightly off-topic, is there a similar disabling of the USB recovery function when HAB-locked? I am using a signed image which runs when loaded into emmc.