DM8168 System MMU (DEMMU) Setup

_Ralph_

Hi, I have a DM8168 with EZSDK 5.02.02.60 and need to know how the DSP gets set up in terms of its MMU and where this occurs.

The three scenarios that I am looking at are:

1) What happens when using a codec server with Codec Engine on the DSP

2) What happens with C6accel (similar to 1 I expect)

3) What happens with C6run (no codec engine).

I can guess that SYS/BIOS probably has the details of MMU setup statically programmed into it (rather than being set by IPC calls to BIOS) so I have read pretty much every document there is on the TI website but am still stuck.

Maybe though, the system MMU is setup just before the DSP binary gets loaded? I don't know.

I've also tried searching through the BIOS folder in the EZSDK for salient memory addresses that might be geting written to but am still stuck. I've also tried to see what cfg files there are in Codec Engine as they may be configuring BIOS but there's far too many to go through manually.

Please could someone help?

Thanks,
Ralph

over 14 years ago

0 Chris Ring over 14 years ago

TI__Genius 17205 points

The DSP's System MMU is [by default] disabled, so memory accesses from the DSP are done using the actual, physical memory addresses.

There are currently no plans to enable that System MMU. But someday, if it is enabled, it will be a system wide policy decision and will be handled the same way the Media Controller's L2 MMU (which _is_ supported) is handled. That is described here:

http://processors.wiki.ti.com/index.php/SysLink_MMU_Support

Chris

0 _Ralph_ over 14 years ago in reply to Chris Ring

Guru 10685 points

Hi Chris,

Thanks for the information. That's what I thought might be true having now done an EZSDK-wide grep for the terms MMU_CFG and MMU_CNTL and following the source code where they occurred, but I wasn't completely certain.

Ralph

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DM8168 System MMU (DEMMU) Setup