Flag D_WBACK

Flag D_WBACK

You specify D_WBACK in pfxdevflag to tell lboot that a block driver performs any necessary cache write-back operations through explicit calls to dki_dcache_wb() and related functions (see the dki_dcache_wb(D3) reference page).

When D_WBACK is not present in pfxdevflag, the physiock() function ensures that all cached data related to buf_t structures is written back to main memory before it enters the driver's strategy routine. (See the physiock(D3) reference page and "Entry Point strategy()".)