[mirror_ubuntu-zesty-kernel.git] / usr / Kconfig

#
# Configuration for initramfs
#

config INITRAMFS_SOURCE
	string "Initramfs source file(s)"
	default ""
	help
	  This can be either a single cpio archive with a .cpio suffix or a
	  space-separated list of directories and files for building the
	  initramfs image.  A cpio archive should contain a filesystem archive
	  to be used as an initramfs image.  Directories should contain a
	  filesystem layout to be included in the initramfs image.  Files
	  should contain entries according to the format described by the
	  "usr/gen_init_cpio" program in the kernel tree.

	  When multiple directories and files are specified then the
	  initramfs image will be the aggregate of all of them.

	  See <file:Documentation/early-userspace/README> for more details.

	  If you are not sure, leave it blank.

config INITRAMFS_ROOT_UID
	int "User ID to map to 0 (user root)"
	depends on INITRAMFS_SOURCE!=""
	default "0"
	help
	  This setting is only meaningful if the INITRAMFS_SOURCE is
	  contains a directory.  Setting this user ID (UID) to something
	  other than "0" will cause all files owned by that UID to be
	  owned by user root in the initial ramdisk image.

	  If you are not sure, leave it set to "0".

config INITRAMFS_ROOT_GID
	int "Group ID to map to 0 (group root)"
	depends on INITRAMFS_SOURCE!=""
	default "0"
	help
	  This setting is only meaningful if the INITRAMFS_SOURCE is
	  contains a directory.  Setting this group ID (GID) to something
	  other than "0" will cause all files owned by that GID to be
	  owned by group root in the initial ramdisk image.

	  If you are not sure, leave it set to "0".

config RD_GZIP
	bool "Support initial ramdisks compressed using gzip"
	depends on BLK_DEV_INITRD
	default y
	select DECOMPRESS_GZIP
	help
	  Support loading of a gzip encoded initial ramdisk or cpio buffer.
	  If unsure, say Y.

config RD_BZIP2
	bool "Support initial ramdisks compressed using bzip2"
	default y
	depends on BLK_DEV_INITRD
	select DECOMPRESS_BZIP2
	help
	  Support loading of a bzip2 encoded initial ramdisk or cpio buffer
	  If unsure, say N.

config RD_LZMA
	bool "Support initial ramdisks compressed using LZMA"
	default y
	depends on BLK_DEV_INITRD
	select DECOMPRESS_LZMA
	help
	  Support loading of a LZMA encoded initial ramdisk or cpio buffer
	  If unsure, say N.

config RD_XZ
	bool "Support initial ramdisks compressed using XZ"
	depends on BLK_DEV_INITRD
	default y
	select DECOMPRESS_XZ
	help
	  Support loading of a XZ encoded initial ramdisk or cpio buffer.
	  If unsure, say N.

config RD_LZO
	bool "Support initial ramdisks compressed using LZO"
	default y
	depends on BLK_DEV_INITRD
	select DECOMPRESS_LZO
	help
	  Support loading of a LZO encoded initial ramdisk or cpio buffer
	  If unsure, say N.

config RD_LZ4
	bool "Support initial ramdisks compressed using LZ4"
	default y
	depends on BLK_DEV_INITRD
	select DECOMPRESS_LZ4
	help
	  Support loading of a LZ4 encoded initial ramdisk or cpio buffer
	  If unsure, say N.

choice
	prompt "Built-in initramfs compression mode"
	depends on INITRAMFS_SOURCE!=""
	optional
	help
	  This option allows you to decide by which algorithm the builtin
	  initramfs will be compressed.  Several compression algorithms are
	  available, which differ in efficiency, compression and
	  decompression speed.  Compression speed is only relevant
	  when building a kernel.  Decompression speed is relevant at
	  each boot. Also the memory usage during decompression may become
	  relevant on memory constrained systems. This is usually based on the
	  dictionary size of the algorithm with algorithms like XZ and LZMA
	  featuring large dictionary sizes.

	  High compression options are mostly useful for users who are
	  low on RAM, since it reduces the memory consumption during
	  boot.

	  Keep in mind that your build system needs to provide the appropriate
	  compression tool to compress the generated initram cpio file for
	  embedding.

	  If in doubt, select 'None'

config INITRAMFS_COMPRESSION_NONE
	bool "None"
	help
	  Do not compress the built-in initramfs at all. This may sound wasteful
	  in space, but, you should be aware that the built-in initramfs will be
	  compressed at a later stage anyways along with the rest of the kernel,
	  on those architectures that support this. However, not compressing the
	  initramfs may lead to slightly higher memory consumption during a
	  short time at boot, while both the cpio image and the unpacked
	  filesystem image will be present in memory simultaneously

config INITRAMFS_COMPRESSION_GZIP
	bool "Gzip"
	depends on RD_GZIP
	help
	  Use the old and well tested gzip compression algorithm. Gzip provides
	  a good balance between compression ratio and decompression speed and
	  has a reasonable compression speed. It is also more likely to be
	  supported by your build system as the gzip tool is present by default
	  on most distros.

config INITRAMFS_COMPRESSION_BZIP2
	bool "Bzip2"
	depends on RD_BZIP2
	help
	  It's compression ratio and speed is intermediate. Decompression speed
	  is slowest among the choices. The initramfs size is about 10% smaller
	  with bzip2, in comparison to gzip. Bzip2 uses a large amount of
	  memory. For modern kernels you will need at least 8MB RAM or more for
	  booting.

	  If you choose this, keep in mind that you need to have the bzip2 tool
	  available to be able to compress the initram.

config INITRAMFS_COMPRESSION_LZMA
	bool "LZMA"
	depends on RD_LZMA
	help
	  This algorithm's compression ratio is best but has a large dictionary
	  size which might cause issues in memory constrained systems.
	  Decompression speed is between the other choices. Compression is
	  slowest. The initramfs size is about 33% smaller with LZMA in
	  comparison to gzip.

	  If you choose this, keep in mind that you may need to install the xz
	  or lzma tools to be able to compress the initram.

config INITRAMFS_COMPRESSION_XZ
	bool "XZ"
	depends on RD_XZ
	help
	  XZ uses the LZMA2 algorithm and has a large dictionary which may cause
	  problems on memory constrained systems. The initramfs size is about
	  30% smaller with XZ in comparison to gzip. Decompression speed is
	  better than that of bzip2 but worse than gzip and LZO. Compression is
	  slow.

	  If you choose this, keep in mind that you may need to install the xz
	  tool to be able to compress the initram.

config INITRAMFS_COMPRESSION_LZO
	bool "LZO"
	depends on RD_LZO
	help
	  It's compression ratio is the second poorest amongst the choices. The
	  kernel size is about 10% bigger than gzip. Despite that, it's
	  decompression speed is the second fastest and it's compression speed
	  is quite fast too.

	  If you choose this, keep in mind that you may need to install the lzop
	  tool to be able to compress the initram.

config INITRAMFS_COMPRESSION_LZ4
	bool "LZ4"
	depends on RD_LZ4
	help
	  It's compression ratio is the poorest amongst the choices. The kernel
	  size is about 15% bigger than gzip; however its decompression speed
	  is the fastest.

	  If you choose this, keep in mind that most distros don't provide lz4
	  by default which could cause a build failure.

endchoice

config INITRAMFS_COMPRESSION
	string
	default ""      if INITRAMFS_COMPRESSION_NONE
	default ".gz"   if INITRAMFS_COMPRESSION_GZIP
	default ".bz2"  if INITRAMFS_COMPRESSION_BZIP2
	default ".lzma" if INITRAMFS_COMPRESSION_LZMA
	default ".xz"   if INITRAMFS_COMPRESSION_XZ
	default ".lzo"  if INITRAMFS_COMPRESSION_LZO
	default ".lz4"  if INITRAMFS_COMPRESSION_LZ4
	default ".gz"   if RD_GZIP
	default ".lz4"  if RD_LZ4
	default ".lzo"  if RD_LZO
	default ".xz"   if RD_XZ
	default ".lzma" if RD_LZMA
	default ".bz2"  if RD_BZIP2
	default ""
Commit	Line	Data
dbec4866 SR	1	#
	2	# Configuration for initramfs
	3	#
	4
	5	config INITRAMFS_SOURCE
	6	string "Initramfs source file(s)"
	7	default ""
	8	help
	9	This can be either a single cpio archive with a .cpio suffix or a
	10	space-separated list of directories and files for building the
	11	initramfs image. A cpio archive should contain a filesystem archive
	12	to be used as an initramfs image. Directories should contain a
	13	filesystem layout to be included in the initramfs image. Files
	14	should contain entries according to the format described by the
	15	"usr/gen_init_cpio" program in the kernel tree.
	16
	17	When multiple directories and files are specified then the
	18	initramfs image will be the aggregate of all of them.
	19
0979f378	20	See <file:Documentation/early-userspace/README> for more details.
dbec4866 SR	21
	22	If you are not sure, leave it blank.
	23
	24	config INITRAMFS_ROOT_UID
	25	int "User ID to map to 0 (user root)"
	26	depends on INITRAMFS_SOURCE!=""
	27	default "0"
	28	help
	29	This setting is only meaningful if the INITRAMFS_SOURCE is
	30	contains a directory. Setting this user ID (UID) to something
	31	other than "0" will cause all files owned by that UID to be
	32	owned by user root in the initial ramdisk image.
	33
	34	If you are not sure, leave it set to "0".
	35
	36	config INITRAMFS_ROOT_GID
	37	int "Group ID to map to 0 (group root)"
	38	depends on INITRAMFS_SOURCE!=""
	39	default "0"
	40	help
	41	This setting is only meaningful if the INITRAMFS_SOURCE is
	42	contains a directory. Setting this group ID (GID) to something
	43	other than "0" will cause all files owned by that GID to be
	44	owned by group root in the initial ramdisk image.
	45
	46	If you are not sure, leave it set to "0".
fb9a4ca9 PA	47
fb9a4ca9 PA	48	config RD_GZIP
ec72c666	49	bool "Support initial ramdisks compressed using gzip"
73d8a12f	50	depends on BLK_DEV_INITRD
ec72c666	51	default y
fb9a4ca9 PA	52	select DECOMPRESS_GZIP
	53	help
	54	Support loading of a gzip encoded initial ramdisk or cpio buffer.
	55	If unsure, say Y.
	56
	57	config RD_BZIP2
ec72c666 AK	58	bool "Support initial ramdisks compressed using bzip2"
ec72c666 AK	59	default y
73d8a12f	60	depends on BLK_DEV_INITRD
fb9a4ca9 PA	61	select DECOMPRESS_BZIP2
	62	help
	63	Support loading of a bzip2 encoded initial ramdisk or cpio buffer
	64	If unsure, say N.
	65
	66	config RD_LZMA
ec72c666 AK	67	bool "Support initial ramdisks compressed using LZMA"
ec72c666 AK	68	default y
73d8a12f	69	depends on BLK_DEV_INITRD
fb9a4ca9 PA	70	select DECOMPRESS_LZMA
fb9a4ca9 PA	71	help
55d1d26f	72	Support loading of a LZMA encoded initial ramdisk or cpio buffer
fb9a4ca9	73	If unsure, say N.
ab76f3d7	74
3ebe1243	75	config RD_XZ
ec72c666	76	bool "Support initial ramdisks compressed using XZ"
3ebe1243	77	depends on BLK_DEV_INITRD
ec72c666	78	default y
3ebe1243 LC	79	select DECOMPRESS_XZ
	80	help
	81	Support loading of a XZ encoded initial ramdisk or cpio buffer.
	82	If unsure, say N.
	83
cacb246f	84	config RD_LZO
ec72c666 AK	85	bool "Support initial ramdisks compressed using LZO"
ec72c666 AK	86	default y
cacb246f AT	87	depends on BLK_DEV_INITRD
	88	select DECOMPRESS_LZO
	89	help
	90	Support loading of a LZO encoded initial ramdisk or cpio buffer
	91	If unsure, say N.
	92
e76e1fdf	93	config RD_LZ4
ec72c666 AK	94	bool "Support initial ramdisks compressed using LZ4"
ec72c666 AK	95	default y
e76e1fdf KL	96	depends on BLK_DEV_INITRD
	97	select DECOMPRESS_LZ4
	98	help
	99	Support loading of a LZ4 encoded initial ramdisk or cpio buffer
	100	If unsure, say N.
35e669e1	101
db2aa7fd FBIR	102	choice
	103	prompt "Built-in initramfs compression mode"
	104	depends on INITRAMFS_SOURCE!=""
	105	optional
	106	help
	107	This option allows you to decide by which algorithm the builtin
	108	initramfs will be compressed. Several compression algorithms are
	109	available, which differ in efficiency, compression and
	110	decompression speed. Compression speed is only relevant
	111	when building a kernel. Decompression speed is relevant at
	112	each boot. Also the memory usage during decompression may become
	113	relevant on memory constrained systems. This is usually based on the
	114	dictionary size of the algorithm with algorithms like XZ and LZMA
	115	featuring large dictionary sizes.
	116
	117	High compression options are mostly useful for users who are
	118	low on RAM, since it reduces the memory consumption during
	119	boot.
	120
	121	Keep in mind that your build system needs to provide the appropriate
	122	compression tool to compress the generated initram cpio file for
	123	embedding.
	124
	125	If in doubt, select 'None'
	126
	127	config INITRAMFS_COMPRESSION_NONE
	128	bool "None"
	129	help
	130	Do not compress the built-in initramfs at all. This may sound wasteful
	131	in space, but, you should be aware that the built-in initramfs will be
	132	compressed at a later stage anyways along with the rest of the kernel,
	133	on those architectures that support this. However, not compressing the
	134	initramfs may lead to slightly higher memory consumption during a
	135	short time at boot, while both the cpio image and the unpacked
	136	filesystem image will be present in memory simultaneously
	137
	138	config INITRAMFS_COMPRESSION_GZIP
	139	bool "Gzip"
	140	depends on RD_GZIP
	141	help
	142	Use the old and well tested gzip compression algorithm. Gzip provides
	143	a good balance between compression ratio and decompression speed and
	144	has a reasonable compression speed. It is also more likely to be
	145	supported by your build system as the gzip tool is present by default
	146	on most distros.
	147
	148	config INITRAMFS_COMPRESSION_BZIP2
	149	bool "Bzip2"
	150	depends on RD_BZIP2
	151	help
	152	It's compression ratio and speed is intermediate. Decompression speed
	153	is slowest among the choices. The initramfs size is about 10% smaller
	154	with bzip2, in comparison to gzip. Bzip2 uses a large amount of
	155	memory. For modern kernels you will need at least 8MB RAM or more for
	156	booting.
	157
	158	If you choose this, keep in mind that you need to have the bzip2 tool
	159	available to be able to compress the initram.
	160
	161	config INITRAMFS_COMPRESSION_LZMA
	162	bool "LZMA"
	163	depends on RD_LZMA
	164	help
	165	This algorithm's compression ratio is best but has a large dictionary
166	size which might cause issues in memory constrained systems.
167	Decompression speed is between the other choices. Compression is
168	slowest. The initramfs size is about 33% smaller with LZMA in
169	comparison to gzip.
170
171	If you choose this, keep in mind that you may need to install the xz
172	or lzma tools to be able to compress the initram.
173
174	config INITRAMFS_COMPRESSION_XZ
175	bool "XZ"
176	depends on RD_XZ
177	help
178	XZ uses the LZMA2 algorithm and has a large dictionary which may cause
179	problems on memory constrained systems. The initramfs size is about
180	30% smaller with XZ in comparison to gzip. Decompression speed is
181	better than that of bzip2 but worse than gzip and LZO. Compression is
182	slow.
183
184	If you choose this, keep in mind that you may need to install the xz
185	tool to be able to compress the initram.
186
187	config INITRAMFS_COMPRESSION_LZO
188	bool "LZO"
189	depends on RD_LZO
190	help
191	It's compression ratio is the second poorest amongst the choices. The
192	kernel size is about 10% bigger than gzip. Despite that, it's
193	decompression speed is the second fastest and it's compression speed
194	is quite fast too.
195
196	If you choose this, keep in mind that you may need to install the lzop
197	tool to be able to compress the initram.
198
199	config INITRAMFS_COMPRESSION_LZ4
200	bool "LZ4"
201	depends on RD_LZ4
202	help
203	It's compression ratio is the poorest amongst the choices. The kernel
204	size is about 15% bigger than gzip; however its decompression speed
205	is the fastest.
206
207	If you choose this, keep in mind that most distros don't provide lz4
208	by default which could cause a build failure.
209
210	endchoice
211
35e669e1 FBIR	212	config INITRAMFS_COMPRESSION
35e669e1 FBIR	213	string
db2aa7fd FBIR	214	default "" if INITRAMFS_COMPRESSION_NONE
	215	default ".gz" if INITRAMFS_COMPRESSION_GZIP
	216	default ".bz2" if INITRAMFS_COMPRESSION_BZIP2
	217	default ".lzma" if INITRAMFS_COMPRESSION_LZMA
	218	default ".xz" if INITRAMFS_COMPRESSION_XZ
	219	default ".lzo" if INITRAMFS_COMPRESSION_LZO
	220	default ".lz4" if INITRAMFS_COMPRESSION_LZ4
35e669e1 FBIR	221	default ".gz" if RD_GZIP
	222	default ".lz4" if RD_LZ4
	223	default ".lzo" if RD_LZO
	224	default ".xz" if RD_XZ
	225	default ".lzma" if RD_LZMA
	226	default ".bz2" if RD_BZIP2
	227	default ""