XScale Mini Data Cache and Page descriptor X bit support

QNX DEVELOPERS Realtime and Embedded
1

Hi,

I am using QNX 6.3.0 on XScale core inside IXP2805 processor.
XScale supports additional X bit in the page descriptor that enables support of Mini Data Cache and write-through/back configuration for both mini and regular caches.

Two questions:

  1. Does QNX itself (in current or future versions) use mini data cache for any purpose?

  2. How can I, as an application programmer, map memory regions and set those XCB cache controlling bits in the page descriptors?

Theoretically, I can totally override QNX and access those page descriptors manually, but I don’t want to discover that QNX will change them for its own reasons or will use mini data cache for something else that I don’t expect.

TIA