cmem memory configuration in EZSDK CE examples

Gaston Schelotto

Hello,

In order to run the Codec Engine Examples the EZSDK Software Developers Guide indicates that cmemk should be installed as follows:

cmemk phys_start=0x94000000 phys_end=0x947fffff pools=20x4096,10x131072,2x1048576

Why cmemk is configured that way? 20 pools of 4Kb, 10 pools of 128Kb and 2 pools of 1024Kb (total: 3408Kb)

In addition phys_start is set to 0x94000000. To which address corresponds according to the EZSDK Memory Map? To the Linux memory? Why there are no specific memory regions for Codec Engine usage like C6Accel?

Regards,
gaston

over 13 years ago

0 GAnthony over 13 years ago

TI__Intellectual 2790 points

Gaston:

The apportioning of memory into pools is very application dependent, and therefore, depends on what codecs are going to be running and their I/O buffer size requirements.

The articles here describes some examples for Codec Engine, and gives some info on Linux memory partitioning as well:

http://processors.wiki.ti.com/index.php/Changing_the_DVEVM_memory_map#CMEM:_Contiguous_Memory_Allocator

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

Regards,

- Gil

0 Gaston Schelotto over 13 years ago in reply to GAnthony

Expert 2850 points

Gil,

Thank you for the tips. Anyway I'd like to understand the above cmem geometry in order to run CE examples. Is this an arbitrary configuration that adapts to all of them? I've dug into CE examples and they implement the same algorithm (memcpy) and use the same number of samples for the I/O buffers (1024 bytes).

Last thing, you've post the link related to DVSDK (DVEVM platforms) instead EZSDK (816x/389x EVM). Sometimes both SDKs share the same information but sometimes not. Maybe some of the information I'm looking for could be described in Codec Engine Examples Memory Map where there is no data about the 816x/389x platform.

Regards,
gaston

0 GAnthony over 13 years ago in reply to Gaston Schelotto

TI__Intellectual 2790 points

Gaston:

The cmem parameters are adapted for the EZSDK product. I'm not too familiar with EZSDK, but my guess is the pools are more and larger to accommodate the real codecs being used in the EZSDK versus the Codec Engine memcpy sample codecs.

I see that phys_start=0x94000000 does not exactly correspond to the 0x96C00000 for CMEM listed in the table: http://processors.wiki.ti.com/index.php/EZSDK_Memory_Map#Memory_Map_in_the_current_EZSDK_.28version_5.02_onwards.29 .

The calculation for phys_start address depends on the mem= value in the Linux bootargs, and other things that are reserved before CMEM. My guess is the EZSDK developers tweaked the overall memory map (maybe for an OMX use case - changing the size of the IPC_SR_FRAME_BUFFERS segment).

I scoured around for documentation, and the formulas for setting cmemk params and info for tweaking the memory maps are documented in these various links.

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

http://processors.wiki.ti.com/index.php/Codec_Engine_Server_Integrator_User%27s_Guide#Platform_Memory_Map_Configuration_.28BIOS6.29

http://processors.wiki.ti.com/index.php/Changing_the_DVEVM_memory_map#Designing_the_Memory_Map

I hope this helps.

Regards,

- Gil

0 Gaston Schelotto over 13 years ago in reply to GAnthony

Expert 2850 points

GAnthony said:
The calculation for phys_start address depends on the mem= value in the Linux bootargs, and other things that are reserved before CMEM. My guess is the EZSDK developers tweaked the overall memory map (maybe for an OMX use case - changing the size of the IPC_SR_FRAME_BUFFERS segment).

You're right. The default Linux bootargs for the mem is 364Mb and it matches with the EZSDK memory map (0x80000000+364Mb=0x96C00000). In order to run the CE examples you have to change the mem value to 169Mb so Linux memory falls in the [0x80000000, 0x8A900000] range. This still does not match with phys_start=0x94000000 but it makes more sense. Gil, thank you for your help.

Regards,
gaston

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cmem memory configuration in EZSDK CE examples