How to list options that are currently compiled into your kernel ?

Yes, there is an easy way to check list of options currently compiled in your kernel. It is as simple as that visting “/boot/config-” file. That said, have a look at below snip in my system.

[root@humbles-lap ~]# cat /boot/config-2.6.35.
config-2.6.35.14-97.fc14.x86_64 config-2.6.35.6-48.fc14.x86_64 config-2.6.35.9-64.fc14.x86_64
[root@humbles-lap ~]#

The above are the files which contains information about compiled options of that specific version of the kernel.

This files will have entries like below.

CONFIG_CRC32=y
CONFIG_CRC7=m
CONFIG_LIBCRC32C=m
CONFIG_ZLIB_INFLATE=y
CONFIG_ZLIB_DEFLATE=m
CONFIG_LZO_COMPRESS=m
CONFIG_LZO_DECOMPRESS=y
CONFIG_DECOMPRESS_GZIP=y
CONFIG_DECOMPRESS_BZIP2=y
CONFIG_DECOMPRESS_LZMA=y
CONFIG_DECOMPRESS_LZO=y
CONFIG_GENERIC_ALLOCATOR=y
CONFIG_REED_SOLOMON=m
CONFIG_REED_SOLOMON_DEC16=y
CONFIG_TEXTSEARCH=y
CONFIG_TEXTSEARCH_KMP=m
CONFIG_TEXTSEARCH_BM=m
CONFIG_TEXTSEARCH_FSM=m
CONFIG_BTREE=y
CONFIG_HAS_IOMEM=y
CONFIG_HAS_IOPORT=y
CONFIG_HAS_DMA=y
CONFIG_CHECK_SIGNATURE=y
CONFIG_NLATTR=y
CONFIG_LRU_CACHE=m
# CONFIG_PCI_DEFAULT_USE_CRS is not set

To check my kernel has “KSM” ( Kernel same page merging) support, I would just do something like

[root@humbles-lap ~]# cat /boot/config-2.6.35.14-97.fc14.x86_64 |grep -i ksm
CONFIG_KSM=y
[root@humbles-lap ~]#

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