mount command outputs its usage on correct arguments

Denys Vlasenko vda.linux at
Sat Feb 8 09:43:24 UTC 2014

On Mon, Jan 20, 2014 at 5:27 PM, Dario Bertini <berdario at> wrote:
> BusyBox v1.21.1-jb bionic (2013-07-25 21:23 +0100) multi-call binary.
> I think the .config should be this one:

It works for me. I only changed this in .config:

-CONFIG_EXTRA_CFLAGS="-Os -fno-short-enums -fgcse-after-reload
-frerun-cse-after-loop -frename-registers"

I guess there is no choice but for you to insert
debug printouts in mount_main().

Can you verify that is it *busybox* mount you are using?
The usage string you show looks different. Mine is:

# ./busybox mount sdfg sdfg sdfg
BusyBox v1.22.0.git (2014-02-03 21:04:14 CET) multi-call binary.

Usage: mount [OPTIONS] [-o OPTS] DEVICE NODE

Mount a filesystem. Filesystem autodetection requires /proc.

        -a              Mount all filesystems in fstab
        -f              Dry run
        -v              Verbose
        -r              Read-only mount
        -w              Read-write mount (default)
        -t FSTYPE[,...] Filesystem type(s)
        -O OPT          Mount only filesystems with option OPT (-a only)
-o OPT:
        loop            Ignored (loop devices are autodetected)
        [a]sync         Writes are [a]synchronous
        [no]atime       Disable/enable updates to inode access times
        [no]diratime    Disable/enable atime updates to directories
        [no]relatime    Disable/enable atime updates relative to
modification time
        [no]dev         (Dis)allow use of special device files
        [no]exec        (Dis)allow use of executable files
        [no]suid        (Dis)allow set-user-id-root programs
        [r]shared       Convert [recursively] to a shared subtree
        [r]slave        Convert [recursively] to a slave subtree
        [r]private      Convert [recursively] to a private subtree
        [un]bindable    Make mount point [un]able to be bind mounted
        [r]bind         Bind a file or directory [recursively] to
another location
        move            Relocate an existing mount point
        remount         Remount a mounted filesystem, changing flags
        ro/rw           Same as -r/-w

There are filesystem-specific -o flags.

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