Man1 - mkfs.erofs.1

mkfs.erofs - tool to create an EROFS filesystem

mkfs.erofs [/OPTIONS/] DESTINATION SOURCE

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.

-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:

legacy-compress

Disable “decompression in-place” and “compacted indexes” support, which is used when generating EROFS images for kernel version < 5.3.

force-inode-compact

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

force-inode-extended

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

noinline_data

Don’t inline regular files for FSDAX support (Linux v5.15+).

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).

*-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.

*–max-extent-bytes */#/

Specify maximum decompressed extent size # in bytes.

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>.

mkfs.erofs is part of erofs-utils package and is available from git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git.

*mkfs*(8).