ROM Code Boot Time Measurements

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ROM Code Boot Time Measurements

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NXP Employee
NXP Employee

I want to share some measurements that we did in the office for the initial boot steps, from POR until user code is executed from DDR. Measurements were made with no HAB and don't include Power time, which is device dependent. They cover the following two steps:

  • boot decision
  • fetching of image into DDR.

Platform used: i.MX6Q / Sabre AI

Image SizeSD Class 4 on CPU CARDNAND** on CPU CARDParallel NOR on CPU CARD
2KB32 ms + 79* ms25 ms23 ms
166KB40 ms + 79* ms61 ms56 ms
1MB77 ms + 79* ms247 ms213 ms

* Constant value, measured only once (after SD card insert/platform power up), does not appear for subsequent s/w resets.

** Samsung K9G4G08U0M

Thanks to Andreas S. for help.

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892 次查看
Contributor I

Do you have measurements with HAB?


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892 次查看
NXP Employee
NXP Employee

When using HAB, RSA and SHA run in parallel. Here is an approximation based on measurements - add the following for HAB:

  If authenticated image < 1MB, a constant of 25ms. For i.MX6SoloX, that time could potentially be reduced to half.

  If authenticated image > 1MB, (Image_Size_MB / 1MB) * 25ms.