topic Securing JTAG on i.mx28 in i.MX Processors

Securing JTAG on i.mx28

abhijithsoman — Fri, 15 Dec 2017 03:23:43 GMT

I'm using i.mx283 (i.MX283 Processors|High-Performance|NXP )

Couldn't find any documents on how to disable/partially disable JTAG port.

https://www.nxp.com/docs/en/application-note/AN4686.pdf Is this application note valid for i.mx28?

Is it possible to disable JTAG memory access(keeping boundary scan enabled) ?

Is it possible to do this without any manufacturing tools, directly from the Linux running on the processor?

Thanks,

- Abhijith

Re: Securing JTAG on i.mx28

igorpadykov — Fri, 15 Dec 2017 09:07:32 GMT

Hi Abhijith

yes this is possible burning bit0 fuse on address HW_OCOTP_CUSTCAP described in

sect. 20.4.18 Customer Capability Shadow Register (HW_OCOTP_CUSTCAP) i.MX28 Reference Manual

https://www.nxp.com/docs/en/reference-manual/MCIMX28RM.pdf

Best regards
igor
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Re: Securing JTAG on i.mx28

abhijithsoman — Fri, 15 Dec 2017 10:57:05 GMT

Hi Igor,

Thank you for the answer.

Could you explain, how can I burn the fuse bit from Linux?

-Abhijith