1MKFS.EROFS(1) General Commands Manual MKFS.EROFS(1)
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6 mkfs.erofs - tool to create an EROFS filesystem
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9 mkfs.erofs [OPTIONS] DESTINATION SOURCE
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12 EROFS is a new enhanced lightweight linux read-only filesystem with
13 modern designs (eg. no buffer head, reduced metadata, inline xat‐
14 trs/data, etc.) for scenarios which need high-performance read-only re‐
15 quirements, e.g. Android OS for smartphones and LIVECDs.
16 It also provides fixed-sized output compression support, which improves
18 storage density, keeps relatively higher compression ratios, which is
19 more useful to achieve high performance for embedded devices with lim‐
20 ited memory since it has unnoticable memory overhead and page cache
21 thrashing.
22 mkfs.erofs is used to create such EROFS filesystem DESTINATION image
24 file from SOURCE directory.
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27 -z compression-algorithm [,#]
28 Set an algorithm for file compression, which can be set with an
29 optional compression level separated by a comma.
30 -C max-pcluster-size
32 Specify the maximum size of compress physical cluster in bytes.
33 It may enable big pcluster feature if needed (Linux v5.13+).
34 -d # Specify the level of debugging messages. The default is 2, which
36 shows basic warning messages.
37 -x # Specify the upper limit of an xattr which is still inlined. The
39 default is 2. Disable storing xattrs if < 0.
40 -E extended-option [,...]
42 Set extended options for the filesystem. Extended options are
43 comma separated, and may take an argument using the equals ('=')
44 sign. The following extended options are supported:
45 force-inode-compact
47 Forcely generate compact inodes (32-byte inodes) to
48 output.
49 force-inode-extended
51 Forcely generate extended inodes (64-byte inodes) to
52 output.
53 force-inode-blockmap
55 Forcely generate inode chunk format in 4-byte block
56 address array.
57 force-chunk-indexes
59 Forcely generate inode chunk format in 8-byte chunk
60 indexes (with device id).
61 legacy-compress
63 Drop "inplace decompression" and "compacted indexes"
64 support, which is used to generate compatible EROFS
65 images for Linux v4.19 - 5.3.
66 noinline_data
68 Don't inline regular files to enable FSDAX for these
69 files (Linux v5.15+).
70 ztailpacking
72 Pack the tail part (pcluster) of compressed files
73 into its metadata to save more space and the tail
74 part I/O. (Linux v5.17+)
75 -T # Set all files to the given UNIX timestamp. Reproducible builds
77 requires setting all to a specific one.
78 -U UUID
80 Set the universally unique identifier (UUID) of the filesystem
81 to UUID. The format of the UUID is a series of hex digits sepa‐
82 rated by hyphens, like this:
83 "c1b9d5a2-f162-11cf-9ece-0020afc76f16".
84 --all-root
86 Make all files owned by root.
87 --blobdev file
89 Specify another extra blob device to store chunk-based data.
90 --chunksize #
92 Generate chunk-based files with #-byte chunks.
93 --compress-hints file
95 If the optional --compress-hints file argument is given,
96 mkfs.erofs uses it to apply the per-file compression strategy.
97 Each line is defined by tokens separated by spaces in the fol‐
98 lowing form:
99 <pcluster-in-bytes> <match-pattern>
100 --exclude-path=path
102 Ignore file that matches the exact literal path. You may give
103 multiple `--exclude-path' options.
104 --exclude-regex=regex
106 Ignore files that match the given regular expression. You may
107 give multiple `--exclude-regex` options.
108 --file-contexts=file
110 Specify a file_contexts file to setup / override selinux labels.
111 --force-uid=UID
113 Set all file uids to UID.
114 --force-gid=GID
116 Set all file gids to GID.
117 --help Display this help and exit.
119 --ignore-mtime
121 File modification time is ignored whenever it would cause
122 mkfs.erofs to use extended inodes over compact inodes. When not
123 using a fixed timestamp, this can reduce total metadata size.
124 --max-extent-bytes #
126 Specify maximum decompressed extent size # in bytes.
127 --preserve-mtime
129 File modification time is preserved whenever mkfs.erofs decides
130 to use extended inodes over compact inodes.
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133 This version of mkfs.erofs is written by Li Guifu <blucer‐
134 lee@gmail.com>, Miao Xie <miaoxie@huawei.com> and Gao Xiang <xiang@ker‐
135 nel.org> with continuously improvements from others.
136 This manual page was written by Gao Xiang <xiang@kernel.org>.
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140 mkfs.erofs is part of erofs-utils package and is available from
141 git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git.
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144 mkfs(8).
145 MKFS.EROFS(1)