Quote:
Originally Posted by kam187
Remember the MSM chipset is an all in one app processor. It has baseband, bluetooth, app cpu, wifi baseband etc all built in. (Of course the analogue basebands are external)
The internal memory of the 7200A is used to map various buffers that all these things use. Memory is then attached on an external bus to expand this memory. However the MMU cannot map certain things to this external bus. Its a limitation by design.
When I say framebuffer I am not talking about the buffer exposed to linux but internal buffers used for things like 3d acceleration. For example your 256mb ATI graphics card on your PC doesnt have a 256mb frame buffer 
It is highly unlikely that there are 32mb and 64mb revisions out there. They will all either be 32mb or 64mb. I just had a look at a firmware image and amss section is 20mb, but that is most likely compressed.
Its possible they are using the 32mb die, but in my opinion very unlikely.
Remember because of the nature of these integrated APP processors ALL memory is shared by the peripherals. Its not dynamic but staticly allocated by the MMU. |
Still confused though, I'd think that the processor would need a window to read/write to that memory. I suppose I'll have to look more closely at how the msm video driver works. It seems surprising that the platform needs 83MB of memory that the kernel never sees.