Cache Consistency

Various functions for cache consistency. More...

Collaboration diagram for Cache Consistency:

Functions
int	l4_cache_clean_data (unsigned long start, unsigned long end) L4_NOTHROW
	Cache clean a range in D-cache; writes back to PoC.
int	l4_cache_flush_data (unsigned long start, unsigned long end) L4_NOTHROW
	Cache flush a range; writes back to PoC.
int	l4_cache_inv_data (unsigned long start, unsigned long end) L4_NOTHROW
	Cache invalidate a range; might write back to PoC.
int	l4_cache_coherent (unsigned long start, unsigned long end) L4_NOTHROW
	Make memory coherent between I-cache and D-cache; writes back to PoU.
int	l4_cache_dma_coherent (unsigned long start, unsigned long end) L4_NOTHROW
	Make memory coherent for use with external memory; writes back to PoC.
int	l4_cache_dma_coherent_full (void) L4_NOTHROW
	Make memory coherent for use with external memory; writes back to PoC.

Detailed Description

Various functions for cache consistency.

These functions shall be used to ensure that

• all blocks (e.g. CPU cores, devices, DMA engines) are guaranteed to see the same copy of a memory location (Point of Coherency – PoC),
• instruction and data caches of a core are guaranteed to see the same copy of a memory location (Point of Unification – PoU).

Certain functions are NOPs on certain architectures, for example on Intel it's not necessary to explicitly make caches coherent to PoU.

Function Documentation

l4_cache_clean_data()

int l4_cache_clean_data ( unsigned long  start, unsigned long  end  )

inline

Cache clean a range in D-cache; writes back to PoC.

Parameters

start	Start of range (inclusive)
end	End of range (exclusive)

Return values

0	on success
-EFAULT	in the case of an unresolved page fault in the given area

Writes back any dirty cache lines in the range but leaves them in the cache and marks the cached copies clean.

Examples

examples/libs/l4re/c++/shared_ds/ds_clnt.cc.

Definition at line 81 of file cache.h.

l4_cache_coherent()

int l4_cache_coherent ( unsigned long  start, unsigned long  end  )

inline

Make memory coherent between I-cache and D-cache; writes back to PoU.

Parameters

start	Start of range (inclusive)
end	End of range (exclusive)

Return values

0	on success
-EFAULT	in the case of an unresolved page fault in the given area

Definition at line 105 of file cache.h.

l4_cache_dma_coherent()

int l4_cache_dma_coherent ( unsigned long  start, unsigned long  end  )

inline

Make memory coherent for use with external memory; writes back to PoC.

Parameters

start	Start of range (inclusive)
end	End of range (exclusive)

Return values

0	on success
-EFAULT	in the case of an unresolved page fault in the given area

Definition at line 113 of file cache.h.

l4_cache_flush_data()

int l4_cache_flush_data ( unsigned long  start, unsigned long  end  )

inline

Cache flush a range; writes back to PoC.

Parameters

start	Start of range (inclusive)
end	End of range (exclusive)

Return values

0	on success
-EFAULT	in the case of an unresolved page fault in the given area

Writes back any dirty cache lines and invalidates all cache entries in the range.

Definition at line 89 of file cache.h.

l4_cache_inv_data()

int l4_cache_inv_data ( unsigned long  start, unsigned long  end  )

inline

Cache invalidate a range; might write back to PoC.

Parameters

start	Start of range (inclusive)
end	End of range (exclusive)

Return values

0	on success
-EFAULT	in the case of an unresolved page fault in the given area

Invalidates all cache entries in the range but does not necessarily write back dirty cache lines.

Note

Implementations may choose to write back dirty lines nonetheless if this is more efficient.

Definition at line 97 of file cache.h.