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Why does Linux fail to boot on NXP i.MX6 or i.MX7 when DS-5 is connected?

Article ID: 218364306

Published date: 04 Jul 2018

Last updated: -

Applies to: DS-5 Development Studio, DSTREAM, ULINKpro


Why does Linux fail to boot on NXP i.MX6 or i.MX7 when DS-5 is connected?


This article might be useful if your development board boots Linux normally when the debugger is not connected, but fails to boot when the debugger is connected.

Typically, the last output from the board when this occurs is :

Starting kernel ...


This could be an issue with the way the kernel was built. During normal boot, references to "caam_sm" such as the following might be seen.

platform caam_sm: blkkey_ex: 8 keystore units available
platform caam_sm: 64-bit clear key:
platform caam_sm: [0000] 00 01 02 03 04 0f 06 07
platform caam_sm: 64-bit black key:
platform caam_sm: [0000] de b1 b3 3e aa 3d b5 f6
platform caam_sm: [0008] 61 ca 44 c6 7d f7 e2 93

The Cryptographic Accelerator and Assurance Module generate these messages. It has the ability to detect that a JTAG probe (such as DSTREAM or ULINKpro) is connected and can prevent the kernel from booting as a security measure.

You can learn how to disable this from the following NXP articles:

You might also find that it is required to pass to the kernel the "clk_ignore_unused" argument. This argument allows the debug power domain to receive a clock which is required to connect the debugger.

More information on this and other kernel parameters can be found at





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