NAME CacheClearE - Cache clearing with extended control (V37) SYNOPSIS CacheClearE(address,length,caches) a0 d0 d1 void CacheClearE(APTR,ULONG,ULONG); FUNCTION Flush out the contents of the CPU instruction and/or data caches. If dirty data cache lines are present, push them to memory first. Motorola CPUs have separate instruction and data caches. A data write does not update the instruction cache. If an instruction is written to memory or modified, the old instruction may still exist in the cache. Before attempting to execute the code, a flush of the instruction cache is required. For most systems, the data cache is not updated by Direct Memory Access (DMA), or if some external factor changes shared memory. Caches must be cleared after *any* operation that could cause invalid or stale data. The most common cases are DMA and modifying instructions using the processor. Some examples: Self modifying code Building Jump tables Run-time code patches Relocating code for use at different addresses. Loading code from disk INPUTS address - Address to start the operation. This may be rounded due to hardware granularity. length - Length of area to be cleared, or $FFFFFFFF to indicate all addresses should be cleared. caches - Bit flags to indicate what caches to affect. The current supported flags are: CACRF_ClearI ;Clear instruction cache CACRF_ClearD ;Clear data cache All other bits are reserved for future definition. NOTES On systems with a copyback mode cache, any dirty data is pushed to memory as a part of this operation. Regardless of the length given, the function will determine the most efficient way to implement the operation. For some cache systems, including the 68030, the overhead partially clearing a cache is often too great. The entire cache may be cleared. For all current Amiga models, Chip memory is set with Instruction caching enabled, data caching disabled. This prevents coherency conflicts with the blitter or other custom chip DMA. Custom chip registers are marked as non-cacheable by the hardware. The system takes care of appropriately flushing the caches for normal operations. The instruction cache is cleared by all calls that modify instructions, including LoadSeg(), MakeLibrary() and SetFunction(). SEE ALSO exec/execbase.i, CacheControl, CacheClearU
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