kernelconfig_penguin
CONFIG_DMA_CACHE_RWFO is not available for the default architecture x86.
Result is shown for architecture arm

Enable read/write for ownership DMA cache maintenance

configname: CONFIG_DMA_CACHE_RWFO

Linux Kernel Configuration
└─> Enable read/write for ownership DMA cache maintenance

The Snoop Control Unit on ARM11MPCore does not detect the
cache maintenance operations and the dma_{map,unmap}_area()
functions may leave stale cache entries on other CPUs. By
enabling this option, Read or Write For Ownership in the ARMv6
DMA cache maintenance functions is performed. These LDR/STR
instructions change the cache line state to shared or modified
so that the cache operation has the desired effect.

Note that the workaround is only valid on processors that do
not perform speculative loads into the D-cache. For such
processors, if cache maintenance operations are not broadcast
in hardware, other workarounds are needed (e.g. cache
maintenance broadcasting in software via FIQ).