The optional WDC instruction (C_ALLOW_DCACHE_WR=1) is used to invalidate or flush cache lines in the data cache from an application. For a detailed description, refer to MicroBlaze Instruction Set Architecture.
The WDC instruction can also be used together with parity protection to periodically invalidate entries the cache, to avoid accumulating errors.
With an external L2 cache, such as the System Cache, connected to MicroBlaze using the ACE interface, external cache invalidate or flush can be performed with WDC. See the System Cache LogiCORE IP Product Guide (PG118) for more information on the System Cache.