RTOS: What should be the cache-able option for shared memory for IPC

Hi there,

is there any way to run this ex02 example with Cache enabled for the heap memory.

Hi Rahul,

so the comment in the ex02 example configuration is wrong. 

It says 

/* Set 0xc4000000 -> 0xc4ffffff to be non-cached for shared memory IPC */
//Cache.MAR192_223 = 0x00000010;

However, its enabled 0xc4000000 -> 0xc4ffffff and the rest is disabled.

How can use the ex02 example with following settings:

Cache.MAR192_223 = 0x00000018;

The entry point of the design is 0xc3000000

Hi Sahin,

When I run the example with defualt cache settings all seems to work. However, when I change the use cache for the messageQ heap the example ex02 design stops working!!!

Could you please help me with this.. How can I use the ex02 example with cache enabled. Thanks. 

DO I need to add cache write back functions? 

Hi there, any update on this issue, please?
Thanks

Hi there, 

In my design I would like to use Cache option for the software running on the DSP. Looking at the example for the IPC it looks like the Cache is disabled for IPC communications.

Is there a way to use Internal On-Chip memory on OMAPL138 address 0x80000000 SharedRam ?

I have added following code in the configuration file:

/* Shared Memory base address and length */
var SHAREDMEM = 0x80001400;
var SHAREDMEMSIZE = 0x00020000;

/*
* Need to define the shared region. The IPC modules use this
* to make portable pointers. All processors need to add this
* call with their base address of the shared memory region.
* If the processor cannot access the memory, do not add it.
*/
var SharedRegion = xdc.useModule('ti.sdo.ipc.SharedRegion');
SharedRegion.setEntryMeta(0,
{ base: SHAREDMEM,
len: SHAREDMEMSIZE,
ownerProcId: 0,
isValid: true,
createHeap: true,
cacheEnable: true,
name: "SharedMem",
});

var HeapMemMP = xdc.useModule('ti.sdo.ipc.heaps.HeapMemMP');
var paramsMP = new HeapMemMP.Params;
paramsMP.name = "shr";
paramsMP.regionId = 0;
paramsMP.sharedAddr = SHAREDMEM;
paramsMP.sharedBufSize = SHAREDMEMSIZE;
var msgHeap1 = HeapMemMP.create(paramsMP);

How can use this buffer as the Heap for MessageQ?

Thanks.

Hi Mitesh,

Sorry for the delayed response. In your SharedRegion configuration, you have createHeap set to "true", which instructs IPC to automatically create a HeapMemMP instance that is the size of the entire shared region. With this configuration, you do not need to create another HeapMemMP instance as you do in your cfg file.

If you want to create a HeapMemMP instance using just a subset of the shared region, then set createHeap to "false" and create the HeapMemMP instance as you do. Just note, the size of the HeapMemMP needs to be less than the SharedRegion.

Also, any IPC instance created within the SharedRegion will inherit the cache settings of the SharedRegion. So since you set cacheEnable to "true", the HeapMemMP instance created will also be cache-enabled. (refer to http://www.ti.com/lit/ug/sprugo6e/sprugo6e.pdf#page=62)

I hope this helps. Please let us know if you have any other questions.

Best,
Sahin

Hi Sahin,

Thanks for coming back.

I have changed the createHeap settings to false and creating heap using the HeapMemMP but the design fails to compile.

Error: HeapMemMP does not support static instances.

Can I do the following:

/* Shared Memory base address and length */
var SHAREDMEM = 0xc0000000;//0x80001400;
var SHAREDMEMSIZE = 0x00020000;

/*
* Need to define the shared region. The IPC modules use this
* to make portable pointers. All processors need to add this
* call with their base address of the shared memory region.
* If the processor cannot access the memory, do not add it.
*/
var SharedRegion = xdc.useModule('ti.sdo.ipc.SharedRegion');
SharedRegion.setEntryMeta(0,
{ base: SHAREDMEM,
len: SHAREDMEMSIZE,
ownerProcId: 0,
isValid: true,
createHeap: false,//true,
cacheEnable: true,
name: "SharedMem",
});

/* create a heap for MessageQ messages */
var HeapBuf = xdc.useModule('ti.sysbios.heaps.HeapBuf');
var params = new HeapBuf.Params;
params.align = 8;
params.blockSize = 512;
params.numBlocks = 256;
//params.sectionName = "testHeap";
var msgHeap = HeapBuf.create(params);

//Program.sectMap["testHeap"] = "SharedMem"; //"DDR";

var MessageQ = xdc.useModule('ti.sdo.ipc.MessageQ');
MessageQ.registerHeapMeta(msgHeap, 0);

But not sure how will msgHeap would be allocated from SharedMem.

Could you please, explain, Thanks.

Happy New Year Sahin, thanks for your reply.

I have gone through the C code of the Messageq_ex02 example. However, when I just make one change

1) 

var Cache = xdc.useModule('ti.sysbios.family.c64p.Cache');
/* Set 0xc4000000 -> 0xc4ffffff to be non-cached for shared memory IPC */
Cache.MAR192_223 = 0x00000010;

to 

var Cache = xdc.useModule('ti.sysbios.family.c64p.Cache');
/* Set 0xc4000000 -> 0xc4ffffff to be non-cached for shared memory IPC */
Cache.MAR192_223 = 0x00000008;

And the example stops working... 

Could you help me to get this working, please.

Hi Sahin, thanks for your reply.

I did try that in the past but I was not able to boot Linux.

Here are the changes I had done:

 * Changed Resource table address for VRINGS to 0xc2000000

 * Changed DSP app to run from 0xc3000000

 * Made 0xc3000000 Cache-able 

 * In DTS file changed CMA region to be 0xc2000000 of lenth 0x02000000

But the linux was not able to boot!/...

Would you be able to create a new ex02 example with cache enabled for the DSP app and VRING in non-cache region for me, please?

Thanks.