Ubuntu Manpage: mkfs.erofs - tool to create an EROFS filesystem

NAME

       mkfs.erofs - tool to create an EROFS filesystem

SYNOPSIS

       mkfs.erofs [OPTIONS] DESTINATION SOURCE

DESCRIPTION

       EROFS is a new enhanced lightweight linux read-only filesystem with modern designs (eg. no
       buffer head, reduced metadata, inline xattrs/data, etc.) for scenarios  which  need  high-
       performance read-only requirements, e.g. Android OS for smartphones and LIVECDs.

       It  also  provides fixed-sized output compression support, which improves storage density,
       keeps relatively  higher  compression  ratios,  which  is  more  useful  to  achieve  high
       performance  for  embedded  devices  with  limited  memory since it has unnoticable memory
       overhead and page cache thrashing.

       mkfs.erofs is used to create such EROFS filesystem  DESTINATION  image  file  from  SOURCE
       directory.

OPTIONS

-z compression-algorithm [,#]
Set an algorithm for file compression, which can be set with an optional
compression level separated by a comma.

-C max-pcluster-size
Specify the maximum size of compress physical cluster in bytes. It may enable big
pcluster feature if needed (Linux v5.13+).

-d # Specify the level of debugging messages. The default is 2, which shows basic
warning messages.

-x # Specify the upper limit of an xattr which is still inlined. The default is 2.
Disable storing xattrs if < 0.

-E extended-option [,...]
Set extended options for the filesystem. Extended options are comma separated, and
may take an argument using the equals ('=') sign. The following extended options
are supported:

force-inode-compact
Forcely generate compact inodes (32-byte inodes) to output.

force-inode-extended
Forcely generate extended inodes (64-byte inodes) to output.

force-inode-blockmap
Forcely generate inode chunk format in 4-byte block address array.

force-chunk-indexes
Forcely generate inode chunk format in 8-byte chunk indexes (with
device id).

legacy-compress
Drop "inplace decompression" and "compacted indexes" support, which is
used to generate compatible EROFS images for Linux v4.19 - 5.3.

noinline_data
Don't inline regular files to enable FSDAX for these files (Linux
v5.15+).

ztailpacking
Pack the tail part (pcluster) of compressed files into its metadata to
save more space and the tail part I/O. (Linux v5.17+)

-T # Set all files to the given UNIX timestamp. Reproducible builds requires setting all
to a specific one.

-U UUID
Set the universally unique identifier (UUID) of the filesystem to UUID. The format
of the UUID is a series of hex digits separated by hyphens, like this:
"c1b9d5a2-f162-11cf-9ece-0020afc76f16".

--all-root
Make all files owned by root.

--blobdev file
Specify another extra blob device to store chunk-based data.

--chunksize #
Generate chunk-based files with #-byte chunks.

--compress-hints file
If the optional --compress-hints file argument is given, mkfs.erofs uses it to
apply the per-file compression strategy. Each line is defined by tokens separated
by spaces in the following form:
<pcluster-in-bytes> <match-pattern>

--exclude-path=path
Ignore file that matches the exact literal path. You may give multiple `--exclude-
path' options.

--exclude-regex=regex
Ignore files that match the given regular expression. You may give multiple
`--exclude-regex` options.

--file-contexts=file
Specify a file_contexts file to setup / override selinux labels.

--force-uid=UID
Set all file uids to UID.

--force-gid=GID
Set all file gids to GID.

--help Display this help and exit.

--ignore-mtime
File modification time is ignored whenever it would cause mkfs.erofs to use
extended inodes over compact inodes. When not using a fixed timestamp, this can
reduce total metadata size.

--max-extent-bytes #
Specify maximum decompressed extent size # in bytes.

--preserve-mtime
File modification time is preserved whenever mkfs.erofs decides to use extended
inodes over compact inodes.

AUTHOR

       This  version  of  mkfs.erofs  is  written  by  Li  Guifu  <blucerlee@gmail.com>, Miao Xie
       <miaoxie@huawei.com> and Gao Xiang <xiang@kernel.org> with continuously improvements  from
       others.

       This manual page was written by Gao Xiang <xiang@kernel.org>.

AVAILABILITY