kernelconfig_penguin
CONFIG_8xx_COPYBACK is not available for the default architecture x86.
Result is shown for architecture powerpc
depends
CONFIG_PPC_8xx

Copy-Back Data Cache (else Writethrough)

configname: CONFIG_8xx_COPYBACK

Linux Kernel Configuration
└─> MPC8xx CPM Options
└─> Copy-Back Data Cache (else Writethrough)

Saying Y here will cause the cache on an MPC8xx processor to be used
in Copy-Back mode. If you say N here, it is used in Writethrough
mode.

If in doubt, say Y here.