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ab76f3d771
Impact: Avoids silent environment dependency Make builtin initramfs compression an explicit configurable. The previous version would pick a compression based on the binaries which were installed on the system, which could lead to unexpected results. It is now explicitly configured, and not having the appropriate binaries installed on the build host is simply an error. Signed-off-by: Alain Knaff <alain@knaff.lu> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
136 lines
4.4 KiB
Plaintext
136 lines
4.4 KiB
Plaintext
#
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# Configuration for initramfs
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#
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config INITRAMFS_SOURCE
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string "Initramfs source file(s)"
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default ""
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help
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This can be either a single cpio archive with a .cpio suffix or a
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space-separated list of directories and files for building the
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initramfs image. A cpio archive should contain a filesystem archive
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to be used as an initramfs image. Directories should contain a
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filesystem layout to be included in the initramfs image. Files
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should contain entries according to the format described by the
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"usr/gen_init_cpio" program in the kernel tree.
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When multiple directories and files are specified then the
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initramfs image will be the aggregate of all of them.
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See <file:Documentation/early-userspace/README> for more details.
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If you are not sure, leave it blank.
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config INITRAMFS_ROOT_UID
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int "User ID to map to 0 (user root)"
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depends on INITRAMFS_SOURCE!=""
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default "0"
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help
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This setting is only meaningful if the INITRAMFS_SOURCE is
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contains a directory. Setting this user ID (UID) to something
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other than "0" will cause all files owned by that UID to be
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owned by user root in the initial ramdisk image.
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If you are not sure, leave it set to "0".
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config INITRAMFS_ROOT_GID
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int "Group ID to map to 0 (group root)"
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depends on INITRAMFS_SOURCE!=""
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default "0"
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help
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This setting is only meaningful if the INITRAMFS_SOURCE is
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contains a directory. Setting this group ID (GID) to something
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other than "0" will cause all files owned by that GID to be
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owned by group root in the initial ramdisk image.
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If you are not sure, leave it set to "0".
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config RD_GZIP
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bool "Initial ramdisk compressed using gzip"
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default y
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depends on BLK_DEV_INITRD=y
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select DECOMPRESS_GZIP
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help
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Support loading of a gzip encoded initial ramdisk or cpio buffer.
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If unsure, say Y.
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config RD_BZIP2
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bool "Initial ramdisk compressed using bzip2"
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default n
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depends on BLK_DEV_INITRD=y
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select DECOMPRESS_BZIP2
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help
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Support loading of a bzip2 encoded initial ramdisk or cpio buffer
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If unsure, say N.
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config RD_LZMA
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bool "Initial ramdisk compressed using lzma"
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default n
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depends on BLK_DEV_INITRD=y
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select DECOMPRESS_LZMA
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help
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Support loading of a lzma encoded initial ramdisk or cpio buffer
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If unsure, say N.
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choice
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prompt "Built-in initramfs compression mode"
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help
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This setting is only meaningful if the INITRAMFS_SOURCE is
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set. It decides by which algorithm the INITRAMFS_SOURCE will
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be compressed.
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Several compression algorithms are available, which differ
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in efficiency, compression and decompression speed.
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Compression speed is only relevant when building a kernel.
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Decompression speed is relevant at each boot.
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If you have any problems with bzip2 or lzma compressed
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initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
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High compression options are mostly useful for users who
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are low on disk space (embedded systems), but for whom ram
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size matters less.
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If in doubt, select 'gzip'
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config INITRAMFS_COMPRESSION_NONE
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bool "None"
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help
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Do not compress the built-in initramfs at all. This may
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sound wasteful in space, but, you should be aware that the
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built-in initramfs will be compressed at a later stage
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anyways along with the rest of the kernel, on those
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architectures that support this.
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However, not compressing the initramfs may lead to slightly
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higher memory consumption during a short time at boot, while
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both the cpio image and the unpacked filesystem image will
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be present in memory simultaneously
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config INITRAMFS_COMPRESSION_GZIP
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bool "Gzip"
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depends on RD_GZIP
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help
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The old and tried gzip compression. Its compression ratio is
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the poorest among the 3 choices; however its speed (both
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compression and decompression) is the fastest.
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config INITRAMFS_COMPRESSION_BZIP2
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bool "Bzip2"
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depends on RD_BZIP2
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help
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Its compression ratio and speed is intermediate.
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Decompression speed is slowest among the three. The initramfs
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size is about 10% smaller with bzip2, in comparison to gzip.
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Bzip2 uses a large amount of memory. For modern kernels you
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will need at least 8MB RAM or more for booting.
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config INITRAMFS_COMPRESSION_LZMA
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bool "LZMA"
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depends on RD_LZMA
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help
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The most recent compression algorithm.
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Its ratio is best, decompression speed is between the other
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two. Compression is slowest. The initramfs size is about 33%
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smaller with LZMA in comparison to gzip.
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endchoice
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