topic Re: i.MX6 Linux usage of OCRAM in i.MX Processors

i.MX6 Linux usage of OCRAM

vsiles — Thu, 05 Jan 2017 08:24:00 GMT

Hi !

We are running a secure OS alongside Linux on some different flavors of i.MX6 boards, and we need to use the OCRAM from the Secure Side. I want to protect the code/data we put on the OCRAM using the provided OCRAM_TZASC. But I am not 100% sure about some behavior of Linux:

* Is Linux using the OCRAM at all ? (maybe for some low power/ suspend features ?)

* If Linux is using the OCRAM, where can I find this in the code, so I can survey how much memory is needed, and I can put our secure information in a different location, so we don't fight over memory

* Is the total amount of OCRAM is 256 Kb ? I'm not sure about the "OCRAM aliased" entry in the memory table.

For your information, we are using 2 flavors of Linux:

* one from NXP: git://git.freescale.com/imx/linux-2.6-imx.git

* one from Boundary Devices (for our sabre lite boards): git://github.com/boundarydevices/linux-imx6.git

Best,

Re: i.MX6 Linux usage of OCRAM

igorpadykov — Fri, 06 Jan 2017 03:58:59 GMT

Hi Vincent

for memory usage please refer to Chapter 3 Machine Specific Layer (MSL)

attached Linux Manual. Yes Linux uses the OCRAM, i.MX6Q OCRAM is 256 KB,

"alias" means the same memory mapped on other address.

Best regards
igor
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Re: i.MX6 Linux usage of OCRAM

vsiles — Fri, 06 Jan 2017 08:13:37 GMT

Hi !

Thank you for the document, it gave me hints on which file to parse. I'll try to see how much OCRAM linux is using, so I can reserve some for secure usage.