.IX \f4dcache_sync\fP(D3DK)

NAME

dcache_sync − sync the data cache

SYNOPSIS

#include <sys/types.h>
#include <sys/buf.h>
#include <sys/iosystm.h>
void dcache_sync(paddr_t paddr int len);

ARGUMENTS

paddrthe physical address of the first location

lenthe number of bytes to be synced

DESCRIPTION

When the standard driver support routines that automatically sync the cache (for example, bp_iosetup) are not used, dcache_sync should be called to perform explicit cache sync operations if the target memory is not cache-inhibited. 

If data is being written to a device, the data cache must be synced after a kernel write to device memory or before a write DMA transfer is initiated to ensure that the device will receive the non-stale data.  Note that no other reads or writes should occur until the DMA transfer is completed. 

If data is being read from a device, the data cache must be synced if any transferred data might be in the cache rather than in memory (that is, if the driver copied the data into the destination rather than using DMA). 

On systems that implement bus snooping, dcache_sync has no effect. 

RETURN VALUE

None. 

LEVEL

Base, interrupt. 

SEE ALSO

dcache_inval(D3DK)

DDI/DKI