i.MX ProcessorsのトピックRe: Random delays(upto 6 minutes) after closed the board for secure boot.

Random delays(upto 6 minutes) after closed the board for secure boot.

krishnanpv — Tue, 12 Dec 2017 11:31:42 GMT

Hi,

I have enabled Secure boot on i.MX6 Dual Lite custom board. I have enabled RNG_TRIM fuse and closed for secure boot. However, I see a strange behavior like occasionally the board is not able to boot up. TThis behavior observed in only on the boards which are closed for secure boot. The board has PMIC chip to control the supply of various voltage levels.

I have gone through the datasheet (Section 4.3.2.2 LDO_2P5 ( In i.MX6 Dual Lite datasheet)) that mention about the voltage requirement. Can anyone experienced similar problems? I am particularly interested in the voltage levels and clocks needed for secure boot and OCOTP controller.

Thanks in Advance,

Krishnan.

Re: Random delays(upto 6 minutes) after closed the board for secure boot.

Yuri — Wed, 13 Dec 2017 06:18:58 GMT

Hello,

Please refer to section 3.3.2 (RNG Trim fuses) of app note AN4581,

Secure Boot on i.MX50, i.MX53, and i.MX 6 Series using HABv4, Rev. 1, 10/2015

https://www.nxp.com/docs/en/application-note/AN4581.pdf

Have a great day,
Yuri

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Re: Random delays(upto 6 minutes) after closed the board for secure boot.

krishnanpv — Tue, 26 Dec 2017 07:28:48 GMT

Hello Yuri,

In the application note, it says deferring the instantiation of RNG is a recommended option. This can be achieved by adding below lines in CSF configuration.

[Unlock]

Engine = CAAM

Features = RNG

However the below line in the AN4581 made me little obscure.

"This does not affect HAB-signed or encrypted boot features. Until the device is closed, HAB does not instantiate the RNG at boot."

In my case, I have closed the device for secure boot. So will the deferring of RNG instantiation will reduce the boot time in my case?

Thanks,

Krishnan.

Re: Random delays(upto 6 minutes) after closed the board for secure boot.

Yuri — Tue, 26 Dec 2017 08:54:22 GMT

Hello,

Since Your device is closed, HAB does instantiate the RNG at boot and it

may take some time. For Linux it also will take some time, but we can hope

smaller.

Regards,

Yuri.