i.MX RT1051 + mbedTLS + TLS 1.2 + DCP

[mathieu_bordere]

Hi,

I'm trying to setup a TLS 1.2 connection with mbedTLS on a i.MX RT1051 with Hardware/DCP accelerated AES128 and SHA256.

For this to work I need to setup the mbedTLS heap allocator to use non-cached memory that can be accessed by the DCP.

When I place the mbedTLS heap in DTCM memory, I'm able to setup a TLS connection and all seems to work fine, however when I move the mbedTLS heap to non-cached SDRAM I fail to setup a TLS connection.

Non-cached SDRAM is setup like this in the MPU

/* Region 9 setting, set last 2MB of SDRAM can't be accessed by cache, local variables which are not expected to be accessed by cache can be put here */
    MPU->RBAR = ARM_MPU_RBAR(9, 0x81E00000U);
    MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 1, 0, 0, 0, 0, ARM_MPU_REGION_SIZE_2MB);

Is this the correct setting?

[jeremyzhou]

Hi Mathieu Borderé,

Thank you for your interest in NXP Semiconductor products and
for the opportunity to serve you.
Yes, it's correct.

Have a great day,
TIC

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[paolo_chiesa]

I have a similar problem: i'm able to run the demo of mbedtls client on imxrt1050 ONLY when disabling cache, but I'm not able to run the same demo with cache enabled because of the DCP/DMA access to cache.

How can I move MBEDTLS on a one not cacheable section? I have already declared a uncacheable section.

[jeremyzhou]

Hi Paolo Chiesa,

To provide the fastest possible support, I'd highly recommend you to refer to the application note:
https://www.nxp.com/docs/en/application-note/AN12042.pdf for details.

Have a great day,
TIC

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