Invalidate & Clean Operations; Global Clean And Invalidate Operation - Intel PXA255 User Manual

Data Cache
6.3.3 Invalidate & Clean Operations
Individual entries can be cleaned and invalidated in the data cache and mini-data cache via
coprocessor 15, register 7. Note that a line locked into the data cache remains locked even after it
has been subjected to an invalidate-entry operation. This will leave an unusable line in the cache
until a global unlock or reset has occurred. For this reason, do not use these commands on locked
lines.
This same register also provides the command to invalidate the entire data cache and mini-data
cache. Refer to
global invalidate commands have no effect on lines locked in the data cache. Locked lines must be
unlocked before they can be invalidated. This is accomplished by the Unlock Data Cache
command found in
6.3.3.1

Global Clean and Invalidate Operation

A simple software routine is used to globally clean the data cache. It takes advantage of the line-
allocate data cache operation, which allocates a line into the data cache. This allocation evicts any
cache dirty data back to external memory.
cleaned.
6-8
Table 7-12, "Cache Functions" on page 7-9
Table 7-14, "Cache Lockdown Functions" on page
for a listing of the commands. These
Example 6-2 on page 6-9
Intel® XScale™ Microarchitecture User's Manual
7-11.
shows how data cache can be