TMS320C6678: Can I remap reserved logical memory location by XMC MPAX ?

Snaku Lee26

Part Number: TMS320C6678

Hi,

There are 4GB DDR3 on my board, so I want to remap some reserved logical memory area (e.g. remap 0x5000_0000 to 0x8_8000_0000) to access the external memory, can I use MPAX to remap them?

Thank you,

Snaku

over 6 years ago

0 Yordan Kovachev over 6 years ago

TI__Guru**** 161600 points

Hi,

I've notified the design team. They will post their feedback directly here.

Best Regards,
Yordan

0 lding over 6 years ago in reply to Yordan Kovachev

TI__Guru* 95265 points

Yes, you can.

Regards, Eric

0 Snaku Lee26 over 6 years ago in reply to lding

Intellectual 310 points

Hi Eric,

Thanks for your reply, but I saw this post (https://e2e.ti.com/support/dsp/c6000_multi-core_dsps/f/639/t/408544 ), Titus said "You can't access or run the program on the 'Reserved memory location' and you would get unexpected behavior CPU hung,Emulator hung etc." Does it mean you can not access reserved memory location even you remapped them?

And I tried to remap some reserved logical memory region to DDR3 physical memory space, I can access them without issue, but there is one region ( i.e. 0x0400_0000 ~ 0x07FF_FFFF) generates exception when I access it, the error message as below:

External exception happened. MEXPFLAG[3]=0x80000000.

Event 127: EMC_BUSERR Bus Error Interrupt for global configuration space between 0x01C00000 - 0x07FFFFFF

CFG write status error detected

XID (Transaction ID)= 13

Addressing error

NRP=0x8107b6, NTSR=0x1400d, IRP=0x0, ITSR=0x0, TSCH= 0xa, TSCL= 0xc5af2a62

B3=0x810ac4, A4=0x0, B4= 0x800000, B14= 0x8251d0, B15= 0x819760

Exception happened at a place can not safely return!

Does it protect by MPU or other module?

Thank you,

Snaku

0 Snaku Lee26 over 6 years ago in reply to Snaku Lee26

Intellectual 310 points

I find the reason why MPAX can't translate 0x0400_0000 logical address, this wiki describes XMC MPAX doesn't translate 0x0000_0000 - 0x0BFF_FFFF memory region.

processors.wiki.ti.com/.../MemoryProtectionOnKeystoneDevices

Thank you,

0 lding over 6 years ago in reply to Snaku Lee26

TI__Guru* 95265 points

Hi,

We typical use MPAX to map a portion of MSMC for different cache setting, or segmenting DDR into several regions and mapping those DDR for each core with the same logical address. Given there are enough 32-bit address, we didn't try to map it into a reserved address like 0x5000_0000. If you have use case you can try.

Regards, Eric

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TMS320C6678: Can I remap reserved logical memory location by XMC MPAX ?