Advanced compression options for JFFS2

configname: CONFIG_JFFS2_COMPRESSION_OPTIONS

Linux Kernel Configuration
└─>File systems
└─>Miscellaneous filesystems
└─>Advanced compression options for JFFS2
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
Enabling this option allows you to explicitly choose which
compression modules, if any, are enabled in JFFS2. Removing
compressors can mean you cannot read existing file systems,
and enabling experimental compressors can mean that you
write a file system which cannot be read by a standard kernel.

If unsure, you should _definitely_ say 'N'.