RTOS/66AK2G12: What memory is at 0x0180_0000 (event combiner, EVTMASKREG)

Chuck Peplinski

Part Number: 66AK2G12
Other Parts Discussed in Thread: SYSBIOS

Tool/software: TI-RTOS

To verify the stability of my system I am enabling exceptions on the memory controller for the DSP.

Exception.enableExternalMPC = true;

When I do this, I hit an exception in EventCombiner_disableEvent() called from edma3OsProtectEntry(). The code is apparently:

    volatile UInt *evtMask = (volatile UInt *)EVTMASKREG;
    ...
    evtMask[index] |= 1 << bitpos;

And EVTMASKREG is 0x0180_0000.

This code works fine when the memory protection exception is not enabled, and the debugger shows something there. But my TRM (SPRUHY8F) doesn't show anything there. Apparently I should add a region to the config.bld file that the linker uses to configure all of this. What regions should be exposed?

over 7 years ago

0 Chuck Peplinski over 7 years ago

Genius 5770 points

On further reflection, there is no memory at this location. Looking into the event combiner code.

0 Chuck Peplinski over 7 years ago in reply to Chuck Peplinski

Genius 5770 points

To clarify the question: What memory is the event combiner attempting to access? Is the code correct? How can I make it so this code does not register an illegal memory access?

0 Yordan Kovachev over 7 years ago in reply to Chuck Peplinski

TI__Guru**** 161600 points

Hi,

We're looking into this.

Best Regards,
Yordan

0 lding over 7 years ago in reply to Yordan Kovachev

TI__Guru* 95265 points

Hi,

Please check the C66x CorePac, see the TMS320C66x DSP CorePac User Guide (SPRUGW0). Section 9.5 for register details.

Regards, Eric

0 Chuck Peplinski over 7 years ago in reply to lding

Genius 5770 points

Thanks for pointing me to that. Now can you help me understand why accessing this causes an external exception when Exception.enableExternalMPC = true? This would seem to be a legal memory region. I tried creating a linker section to enable R/W access, but that didn't solve it. What do you think should declare access to this memory legal?

0 lding over 7 years ago in reply to Chuck Peplinski

TI__Guru* 95265 points

Hi,

Sorry for the late, I missed this thread. In the SYSBIOS,
#define EVTFLAGREG 0x01800000
#define EVTSETREG 0x01800020
#define EVTCLRREG 0x01800040
#define EVTMASKREG 0x01800080
#define MEVTFLAGREG 0x018000a0

Checking CorePac user guide, section 9.5, this is EVTMASK0 Event mask register 0 and explained: These registers allow up to 32 events to be combined into a single event output that is used as a single DSP interrupt or AET event. The event mask bits within the EVTMASKn register act as enablers for the received system events to be combined on the event outputs. The value you saw with 0x0180_0000 is not an address, but event bit enabled for combination.

For what address caused the memory protection error, please check section 10.3. There are some good discussions for MPC:
processors.wiki.ti.com/.../MemoryProtectionOnKeystoneDevices
e2e.ti.com/.../212913
e2e.ti.com/.../581462

Regards, Eric

0 Chuck Peplinski over 7 years ago in reply to lding

Genius 5770 points

Related post: e2e.ti.com/.../714489
The .cfg file has to open up access to the component.

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RTOS/66AK2G12: What memory is at 0x0180_0000 (event combiner, EVTMASKREG)