2 # For a description of the syntax of this configuration file,
3 # see scripts/kbuild/config-language.txt.
6 menu "Linux System Utilities"
8 config BUSYBOX_CONFIG_ACPID
12 acpid listens to ACPI events coming either in textual form from
13 /proc/acpi/event (though it is marked deprecated it is still widely
14 used and _is_ a standard) or in binary form from specified evdevs
15 (just use /dev/input/event*).
17 It parses the event to retrieve ACTION and a possible PARAMETER.
18 It then spawns /etc/acpi/<ACTION>[/<PARAMETER>] either via run-parts
19 (if the resulting path is a directory) or directly as an executable.
21 N.B. acpid relies on run-parts so have the latter installed.
23 config BUSYBOX_CONFIG_FEATURE_ACPID_COMPAT
24 bool "Accept and ignore redundant options"
26 depends on BUSYBOX_CONFIG_ACPID
28 Accept and ignore compatibility options -g -m -s -S -v.
30 config BUSYBOX_CONFIG_BLKID
33 select BUSYBOX_CONFIG_VOLUMEID
35 Lists labels and UUIDs of all filesystems.
37 With all submodules selected, it will add ~8k to busybox.
39 config BUSYBOX_CONFIG_DMESG
43 dmesg is used to examine or control the kernel ring buffer. When the
44 Linux kernel prints messages to the system log, they are stored in
45 the kernel ring buffer. You can use dmesg to print the kernel's ring
46 buffer, clear the kernel ring buffer, change the size of the kernel
47 ring buffer, and change the priority level at which kernel messages
48 are also logged to the system console. Enable this option if you
49 wish to enable the 'dmesg' utility.
51 config BUSYBOX_CONFIG_FEATURE_DMESG_PRETTY
52 bool "Pretty dmesg output"
54 depends on BUSYBOX_CONFIG_DMESG
56 If you wish to scrub the syslog level from the output, say 'Y' here.
57 The syslog level is a string prefixed to every line with the form
60 With this option you will see:
62 Linux version 2.6.17.4 .....
63 BIOS-provided physical RAM map:
64 BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
66 Without this option you will see:
68 <5>Linux version 2.6.17.4 .....
69 <6>BIOS-provided physical RAM map:
70 <6> BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
72 config BUSYBOX_CONFIG_FBSET
76 fbset is used to show or change the settings of a Linux frame buffer
77 device. The frame buffer device provides a simple and unique
78 interface to access a graphics display. Enable this option
79 if you wish to enable the 'fbset' utility.
81 config BUSYBOX_CONFIG_FEATURE_FBSET_FANCY
82 bool "Turn on extra fbset options"
84 depends on BUSYBOX_CONFIG_FBSET
86 This option enables extended fbset options, allowing one to set the
87 framebuffer size, color depth, etc. interface to access a graphics
88 display. Enable this option if you wish to enable extended fbset
91 config BUSYBOX_CONFIG_FEATURE_FBSET_READMODE
92 bool "Turn on fbset readmode support"
94 depends on BUSYBOX_CONFIG_FBSET
96 This option allows fbset to read the video mode database stored by
97 default n /etc/fb.modes, which can be used to set frame buffer
98 device to pre-defined video modes.
100 config BUSYBOX_CONFIG_FDFLUSH
104 fdflush is only needed when changing media on slightly-broken
105 removable media drives. It is used to make Linux believe that a
106 hardware disk-change switch has been actuated, which causes Linux to
107 forget anything it has cached from the previous media. If you have
108 such a slightly-broken drive, you will need to run fdflush every time
109 you change a disk. Most people have working hardware and can safely
112 config BUSYBOX_CONFIG_FDFORMAT
116 fdformat is used to low-level format a floppy disk.
118 config BUSYBOX_CONFIG_FDISK
122 The fdisk utility is used to divide hard disks into one or more
123 logical disks, which are generally called partitions. This utility
124 can be used to list and edit the set of partitions or BSD style
125 'disk slices' that are defined on a hard drive.
127 config BUSYBOX_CONFIG_FDISK_SUPPORT_LARGE_DISKS
128 bool "Support over 4GB disks"
130 depends on BUSYBOX_CONFIG_FDISK
132 Enable this option to support large disks > 4GB.
134 config BUSYBOX_CONFIG_FEATURE_FDISK_WRITABLE
137 depends on BUSYBOX_CONFIG_FDISK
139 Enabling this option allows you to create or change a partition table
140 and write those changes out to disk. If you leave this option
141 disabled, you will only be able to view the partition table.
143 config BUSYBOX_CONFIG_FEATURE_AIX_LABEL
144 bool "Support AIX disklabels"
146 depends on BUSYBOX_CONFIG_FDISK && BUSYBOX_CONFIG_FEATURE_FDISK_WRITABLE
148 Enabling this option allows you to create or change AIX disklabels.
149 Most people can safely leave this option disabled.
151 config BUSYBOX_CONFIG_FEATURE_SGI_LABEL
152 bool "Support SGI disklabels"
154 depends on BUSYBOX_CONFIG_FDISK && BUSYBOX_CONFIG_FEATURE_FDISK_WRITABLE
156 Enabling this option allows you to create or change SGI disklabels.
157 Most people can safely leave this option disabled.
159 config BUSYBOX_CONFIG_FEATURE_SUN_LABEL
160 bool "Support SUN disklabels"
162 depends on BUSYBOX_CONFIG_FDISK && BUSYBOX_CONFIG_FEATURE_FDISK_WRITABLE
164 Enabling this option allows you to create or change SUN disklabels.
165 Most people can safely leave this option disabled.
167 config BUSYBOX_CONFIG_FEATURE_OSF_LABEL
168 bool "Support BSD disklabels"
170 depends on BUSYBOX_CONFIG_FDISK && BUSYBOX_CONFIG_FEATURE_FDISK_WRITABLE
172 Enabling this option allows you to create or change BSD disklabels
173 and define and edit BSD disk slices.
175 config BUSYBOX_CONFIG_FEATURE_FDISK_ADVANCED
176 bool "Support expert mode"
178 depends on BUSYBOX_CONFIG_FDISK && BUSYBOX_CONFIG_FEATURE_FDISK_WRITABLE
180 Enabling this option allows you to do terribly unsafe things like
181 define arbitrary drive geometry, move the beginning of data in a
182 partition, and similarly evil things. Unless you have a very good
183 reason you would be wise to leave this disabled.
185 config BUSYBOX_CONFIG_FINDFS
188 select BUSYBOX_CONFIG_VOLUMEID
190 Prints the name of a filesystem with given label or UUID.
192 With all submodules selected, it will add ~8k to busybox.
194 config BUSYBOX_CONFIG_FREERAMDISK
198 Linux allows you to create ramdisks. This utility allows you to
199 delete them and completely free all memory that was used for the
200 ramdisk. For example, if you boot Linux into a ramdisk and later
201 pivot_root, you may want to free the memory that is allocated to the
202 ramdisk. If you have no use for freeing memory from a ramdisk, leave
205 config BUSYBOX_CONFIG_FSCK_MINIX
209 The minix filesystem is a nice, small, compact, read-write filesystem
210 with little overhead. It is not a journaling filesystem however and
211 can experience corruption if it is not properly unmounted or if the
212 power goes off in the middle of a write. This utility allows you to
213 check for and attempt to repair any corruption that occurs to a minix
216 config BUSYBOX_CONFIG_MKFS_MINIX
220 The minix filesystem is a nice, small, compact, read-write filesystem
221 with little overhead. If you wish to be able to create minix
222 filesystems this utility will do the job for you.
224 comment "Minix filesystem support"
225 depends on BUSYBOX_CONFIG_FSCK_MINIX || BUSYBOX_CONFIG_MKFS_MINIX
227 config BUSYBOX_CONFIG_FEATURE_MINIX2
228 bool "Support Minix fs v2 (fsck_minix/mkfs_minix)"
230 depends on BUSYBOX_CONFIG_FSCK_MINIX || BUSYBOX_CONFIG_MKFS_MINIX
232 If you wish to be able to create version 2 minix filesystems, enable
233 this. If you enabled 'mkfs_minix' then you almost certainly want to
234 be using the version 2 filesystem support.
236 config BUSYBOX_CONFIG_MKFS_VFAT
240 Utility to create FAT32 filesystems.
242 config BUSYBOX_CONFIG_GETOPT
246 The getopt utility is used to break up (parse) options in command
247 lines to make it easy to write complex shell scripts that also check
248 for legal (and illegal) options. If you want to write horribly
249 complex shell scripts, or use some horribly complex shell script
250 written by others, this utility may be for you. Most people will
251 wisely leave this disabled.
253 config BUSYBOX_CONFIG_FEATURE_GETOPT_LONG
254 bool "Support option -l"
255 default n if BUSYBOX_CONFIG_LONG_OPTS
256 depends on BUSYBOX_CONFIG_GETOPT
258 Enable support for long options (option -l).
260 config BUSYBOX_CONFIG_HEXDUMP
264 The hexdump utility is used to display binary data in a readable
265 way that is comparable to the output from most hex editors.
267 config BUSYBOX_CONFIG_FEATURE_HEXDUMP_REVERSE
268 bool "Support -R, reverse of 'hexdump -Cv'"
270 depends on BUSYBOX_CONFIG_HEXDUMP
272 The hexdump utility is used to display binary data in an ascii
273 readable way. This option creates binary data from an ascii input.
274 NB: this option is non-standard. It's unwise to use it in scripts
275 aimed to be portable.
277 config BUSYBOX_CONFIG_HD
280 select BUSYBOX_CONFIG_HEXDUMP
282 hd is an alias to hexdump -C.
284 config BUSYBOX_CONFIG_HWCLOCK
288 The hwclock utility is used to read and set the hardware clock
289 on a system. This is primarily used to set the current time on
290 shutdown in the hardware clock, so the hardware will keep the
291 correct time when Linux is _not_ running.
293 config BUSYBOX_CONFIG_FEATURE_HWCLOCK_LONG_OPTIONS
294 bool "Support long options (--hctosys,...)"
296 depends on BUSYBOX_CONFIG_HWCLOCK && BUSYBOX_CONFIG_LONG_OPTS
298 By default, the hwclock utility only uses short options. If you
299 are overly fond of its long options, such as --hctosys, --utc, etc)
300 then enable this option.
302 config BUSYBOX_CONFIG_FEATURE_HWCLOCK_ADJTIME_FHS
303 bool "Use FHS /var/lib/hwclock/adjtime"
305 depends on BUSYBOX_CONFIG_HWCLOCK
307 Starting with FHS 2.3, the adjtime state file is supposed to exist
308 at /var/lib/hwclock/adjtime instead of /etc/adjtime. If you wish
309 to use the FHS behavior, answer Y here, otherwise answer N for the
310 classic /etc/adjtime path.
312 pathname.com/fhs/pub/fhs-2.3.html#VARLIBHWCLOCKSTATEDIRECTORYFORHWCLO
314 config BUSYBOX_CONFIG_IPCRM
317 select BUSYBOX_CONFIG_FEATURE_SUID
319 The ipcrm utility allows the removal of System V interprocess
320 communication (IPC) objects and the associated data structures
323 config BUSYBOX_CONFIG_IPCS
326 select BUSYBOX_CONFIG_FEATURE_SUID
328 The ipcs utility is used to provide information on the currently
329 allocated System V interprocess (IPC) objects in the system.
331 config BUSYBOX_CONFIG_LOSETUP
335 losetup is used to associate or detach a loop device with a regular
336 file or block device, and to query the status of a loop device. This
337 version does not currently support enabling data encryption.
339 config BUSYBOX_CONFIG_MDEV
343 mdev is a mini-udev implementation for dynamically creating device
344 nodes in the /dev directory.
346 For more information, please see docs/mdev.txt
348 config BUSYBOX_CONFIG_FEATURE_MDEV_CONF
349 bool "Support /etc/mdev.conf"
351 depends on BUSYBOX_CONFIG_MDEV
353 Add support for the mdev config file to control ownership and
354 permissions of the device nodes.
356 For more information, please see docs/mdev.txt
358 config BUSYBOX_CONFIG_FEATURE_MDEV_RENAME
359 bool "Support subdirs/symlinks"
361 depends on BUSYBOX_CONFIG_FEATURE_MDEV_CONF
363 Add support for renaming devices and creating symlinks.
365 For more information, please see docs/mdev.txt
367 config BUSYBOX_CONFIG_FEATURE_MDEV_RENAME_REGEXP
368 bool "Support regular expressions substitutions when renaming device"
370 depends on BUSYBOX_CONFIG_FEATURE_MDEV_RENAME
372 Add support for regular expressions substitutions when renaming
375 config BUSYBOX_CONFIG_FEATURE_MDEV_EXEC
376 bool "Support command execution at device addition/removal"
378 depends on BUSYBOX_CONFIG_FEATURE_MDEV_CONF
380 This adds support for an optional field to /etc/mdev.conf for
381 executing commands when devices are created/removed.
383 For more information, please see docs/mdev.txt
385 config BUSYBOX_CONFIG_FEATURE_MDEV_LOAD_FIRMWARE
386 bool "Support loading of firmwares"
388 depends on BUSYBOX_CONFIG_MDEV
390 Some devices need to load firmware before they can be usable.
392 These devices will request userspace look up the files in
393 /lib/firmware/ and if it exists, send it to the kernel for
394 loading into the hardware.
396 config BUSYBOX_CONFIG_MKSWAP
400 The mkswap utility is used to configure a file or disk partition as
401 Linux swap space. This allows Linux to use the entire file or
402 partition as if it were additional RAM, which can greatly increase
403 the capability of low-memory machines. This additional memory is
404 much slower than real RAM, but can be very helpful at preventing your
405 applications being killed by the Linux out of memory (OOM) killer.
406 Once you have created swap space using 'mkswap' you need to enable
407 the swap space using the 'swapon' utility.
409 config BUSYBOX_CONFIG_FEATURE_MKSWAP_UUID
412 depends on BUSYBOX_CONFIG_MKSWAP
414 Generate swap spaces with universally unique identifiers.
416 config BUSYBOX_CONFIG_MORE
420 more is a simple utility which allows you to read text one screen
421 sized page at a time. If you want to read text that is larger than
422 the screen, and you are using anything faster than a 300 baud modem,
423 you will probably find this utility very helpful. If you don't have
424 any need to reading text files, you can leave this disabled.
426 config BUSYBOX_CONFIG_FEATURE_USE_TERMIOS
427 bool "Use termios to manipulate the screen"
429 depends on BUSYBOX_CONFIG_MORE || BUSYBOX_CONFIG_TOP
431 This option allows utilities such as 'more' and 'top' to determine
432 the size of the screen. If you leave this disabled, your utilities
433 that display things on the screen will be especially primitive and
434 will be unable to determine the current screen size, and will be
435 unable to move the cursor.
437 config BUSYBOX_CONFIG_VOLUMEID
438 bool #No description makes it a hidden option
441 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_EXT
442 bool "Ext filesystem"
444 depends on BUSYBOX_CONFIG_VOLUMEID
448 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_REISERFS
449 bool "Reiser filesystem"
451 depends on BUSYBOX_CONFIG_VOLUMEID
455 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_FAT
456 bool "fat filesystem"
458 depends on BUSYBOX_CONFIG_VOLUMEID
462 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_HFS
463 bool "hfs filesystem"
465 depends on BUSYBOX_CONFIG_VOLUMEID
469 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_JFS
470 bool "jfs filesystem"
472 depends on BUSYBOX_CONFIG_VOLUMEID
476 ### config FEATURE_VOLUMEID_UFS
477 ### bool "ufs filesystem"
479 ### depends on VOLUMEID
483 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_XFS
484 bool "xfs filesystem"
486 depends on BUSYBOX_CONFIG_VOLUMEID
490 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_NTFS
491 bool "ntfs filesystem"
493 depends on BUSYBOX_CONFIG_VOLUMEID
497 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_ISO9660
498 bool "iso9660 filesystem"
500 depends on BUSYBOX_CONFIG_VOLUMEID
504 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_UDF
505 bool "udf filesystem"
507 depends on BUSYBOX_CONFIG_VOLUMEID
511 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_LUKS
512 bool "luks filesystem"
514 depends on BUSYBOX_CONFIG_VOLUMEID
518 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_LINUXSWAP
519 bool "linux swap filesystem"
521 depends on BUSYBOX_CONFIG_VOLUMEID
525 ### config FEATURE_VOLUMEID_LVM
528 ### depends on VOLUMEID
532 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_CRAMFS
533 bool "cramfs filesystem"
535 depends on BUSYBOX_CONFIG_VOLUMEID
539 ### config FEATURE_VOLUMEID_HPFS
540 ### bool "hpfs filesystem"
542 ### depends on VOLUMEID
546 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_ROMFS
547 bool "romfs filesystem"
549 depends on BUSYBOX_CONFIG_VOLUMEID
553 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_SYSV
554 bool "sysv filesystem"
556 depends on BUSYBOX_CONFIG_VOLUMEID
560 ### config FEATURE_VOLUMEID_MINIX
561 ### bool "minix filesystem"
563 ### depends on VOLUMEID
567 ### These only detect partition tables - not used (yet?)
568 ### config FEATURE_VOLUMEID_MAC
569 ### bool "mac filesystem"
571 ### depends on VOLUMEID
575 ### config FEATURE_VOLUMEID_MSDOS
576 ### bool "msdos filesystem"
578 ### depends on VOLUMEID
582 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_OCFS2
583 bool "ocfs2 filesystem"
585 depends on BUSYBOX_CONFIG_VOLUMEID
589 ### config FEATURE_VOLUMEID_HIGHPOINTRAID
590 ### bool "highpoint raid"
592 ### depends on VOLUMEID
596 ### config FEATURE_VOLUMEID_ISWRAID
597 ### bool "intel raid"
599 ### depends on VOLUMEID
603 ### config FEATURE_VOLUMEID_LSIRAID
606 ### depends on VOLUMEID
610 ### config FEATURE_VOLUMEID_VIARAID
613 ### depends on VOLUMEID
617 ### config FEATURE_VOLUMEID_SILICONRAID
618 ### bool "silicon raid"
620 ### depends on VOLUMEID
624 ### config FEATURE_VOLUMEID_NVIDIARAID
625 ### bool "nvidia raid"
627 ### depends on VOLUMEID
631 ### config FEATURE_VOLUMEID_PROMISERAID
632 ### bool "promise raid"
634 ### depends on VOLUMEID
638 config BUSYBOX_CONFIG_FEATURE_VOLUMEID_LINUXRAID
641 depends on BUSYBOX_CONFIG_VOLUMEID
645 config BUSYBOX_CONFIG_MOUNT
649 All files and filesystems in Unix are arranged into one big directory
650 tree. The 'mount' utility is used to graft a filesystem onto a
651 particular part of the tree. A filesystem can either live on a block
652 device, or it can be accessible over the network, as is the case with
653 NFS filesystems. Most people using BusyBox will also want to enable
656 config BUSYBOX_CONFIG_FEATURE_MOUNT_FAKE
657 bool "Support option -f"
659 depends on BUSYBOX_CONFIG_MOUNT
661 Enable support for faking a file system mount.
663 config BUSYBOX_CONFIG_FEATURE_MOUNT_VERBOSE
664 bool "Support option -v"
666 depends on BUSYBOX_CONFIG_MOUNT
668 Enable multi-level -v[vv...] verbose messages. Useful if you
669 debug mount problems and want to see what is exactly passed
672 config BUSYBOX_CONFIG_FEATURE_MOUNT_HELPERS
673 bool "Support mount helpers"
675 depends on BUSYBOX_CONFIG_MOUNT
677 Enable mounting of virtual file systems via external helpers.
678 E.g. "mount obexfs#-b00.11.22.33.44.55 /mnt" will in effect call
679 "obexfs -b00.11.22.33.44.55 /mnt"
680 Also "mount -t sometype [-o opts] fs /mnt" will try
681 "sometype [-o opts] fs /mnt" if simple mount syscall fails.
682 The idea is to use such virtual filesystems in /etc/fstab.
684 config BUSYBOX_CONFIG_FEATURE_MOUNT_LABEL
685 bool "Support specifiying devices by label or UUID"
687 depends on BUSYBOX_CONFIG_MOUNT
688 select BUSYBOX_CONFIG_VOLUMEID
690 This allows for specifying a device by label or uuid, rather than by
691 name. This feature utilizes the same functionality as blkid/findfs.
693 config BUSYBOX_CONFIG_FEATURE_MOUNT_NFS
694 bool "Support mounting NFS file systems"
696 depends on BUSYBOX_CONFIG_MOUNT
697 select BUSYBOX_CONFIG_FEATURE_HAVE_RPC
698 select BUSYBOX_CONFIG_FEATURE_SYSLOG
700 Enable mounting of NFS file systems.
702 config BUSYBOX_CONFIG_FEATURE_MOUNT_CIFS
703 bool "Support mounting CIFS/SMB file systems"
705 depends on BUSYBOX_CONFIG_MOUNT
707 Enable support for samba mounts.
709 config BUSYBOX_CONFIG_FEATURE_MOUNT_FLAGS
710 depends on BUSYBOX_CONFIG_MOUNT
711 bool "Support lots of -o flags in mount"
714 Without this, mount only supports ro/rw/remount. With this, it
715 supports nosuid, suid, dev, nodev, exec, noexec, sync, async, atime,
716 noatime, diratime, nodiratime, loud, bind, move, shared, slave,
717 private, unbindable, rshared, rslave, rprivate, and runbindable.
719 config BUSYBOX_CONFIG_FEATURE_MOUNT_FSTAB
720 depends on BUSYBOX_CONFIG_MOUNT
721 bool "Support /etc/fstab and -a"
724 Support mount all and looking for files in /etc/fstab.
726 config BUSYBOX_CONFIG_PIVOT_ROOT
730 The pivot_root utility swaps the mount points for the root filesystem
731 with some other mounted filesystem. This allows you to do all sorts
732 of wild and crazy things with your Linux system and is far more
733 powerful than 'chroot'.
735 Note: This is for initrd in linux 2.4. Under initramfs (introduced
736 in linux 2.6) use switch_root instead.
738 config BUSYBOX_CONFIG_RDATE
742 The rdate utility allows you to synchronize the date and time of your
743 system clock with the date and time of a remote networked system using
744 the RFC868 protocol, which is built into the inetd daemon on most
747 config BUSYBOX_CONFIG_RDEV
751 Print the device node associated with the filesystem mounted at '/'.
753 config BUSYBOX_CONFIG_READPROFILE
757 This allows you to parse /proc/profile for basic profiling.
759 config BUSYBOX_CONFIG_RTCWAKE
763 Enter a system sleep state until specified wakeup time.
765 config BUSYBOX_CONFIG_SCRIPT
769 The script makes typescript of terminal session.
771 config BUSYBOX_CONFIG_SCRIPTREPLAY
775 This program replays a typescript, using timing information
778 config BUSYBOX_CONFIG_SETARCH
782 The linux32 utility is used to create a 32bit environment for the
783 specified program (usually a shell). It only makes sense to have
784 this util on a system that supports both 64bit and 32bit userland
785 (like amd64/x86, ppc64/ppc, sparc64/sparc, etc...).
787 config BUSYBOX_CONFIG_SWAPONOFF
791 This option enables both the 'swapon' and the 'swapoff' utilities.
792 Once you have created some swap space using 'mkswap', you also need
793 to enable your swap space with the 'swapon' utility. The 'swapoff'
794 utility is used, typically at system shutdown, to disable any swap
795 space. If you are not using any swap space, you can leave this
798 config BUSYBOX_CONFIG_FEATURE_SWAPON_PRI
799 bool "Support priority option -p"
801 depends on BUSYBOX_CONFIG_SWAPONOFF
803 Enable support for setting swap device priority in swapon.
805 config BUSYBOX_CONFIG_SWITCH_ROOT
809 The switch_root utility is used from initramfs to select a new
810 root device. Under initramfs, you have to use this instead of
811 pivot_root. (Stop reading here if you don't care why.)
813 Booting with initramfs extracts a gzipped cpio archive into rootfs
814 (which is a variant of ramfs/tmpfs). Because rootfs can't be moved
815 or unmounted*, pivot_root will not work from initramfs. Instead,
816 switch_root deletes everything out of rootfs (including itself),
817 does a mount --move that overmounts rootfs with the new root, and
818 then execs the specified init program.
820 * Because the Linux kernel uses rootfs internally as the starting
821 and ending point for searching through the kernel's doubly linked
822 list of active mount points. That's why.
824 config BUSYBOX_CONFIG_UMOUNT
828 When you want to remove a mounted filesystem from its current mount
829 point, for example when you are shutting down the system, the
830 'umount' utility is the tool to use. If you enabled the 'mount'
831 utility, you almost certainly also want to enable 'umount'.
833 config BUSYBOX_CONFIG_FEATURE_UMOUNT_ALL
834 bool "Support option -a"
836 depends on BUSYBOX_CONFIG_UMOUNT
838 Support -a option to unmount all currently mounted filesystems.
840 comment "Common options for mount/umount"
841 depends on BUSYBOX_CONFIG_MOUNT || BUSYBOX_CONFIG_UMOUNT
843 config BUSYBOX_CONFIG_FEATURE_MOUNT_LOOP
844 bool "Support loopback mounts"
846 depends on BUSYBOX_CONFIG_MOUNT || BUSYBOX_CONFIG_UMOUNT
848 Enabling this feature allows automatic mounting of files (containing
849 filesystem images) via the linux kernel's loopback devices.
850 The mount command will detect you are trying to mount a file instead
851 of a block device, and transparently associate the file with a
852 loopback device. The umount command will also free that loopback
855 You can still use the 'losetup' utility (to manually associate files
856 with loop devices) if you need to do something advanced, such as
857 specify an offset or cryptographic options to the loopback device.
858 (If you don't want umount to free the loop device, use "umount -D".)
860 config BUSYBOX_CONFIG_FEATURE_MTAB_SUPPORT
861 bool "Support for the old /etc/mtab file"
863 depends on BUSYBOX_CONFIG_MOUNT || BUSYBOX_CONFIG_UMOUNT
864 select BUSYBOX_CONFIG_FEATURE_MOUNT_FAKE
866 Historically, Unix systems kept track of the currently mounted
867 partitions in the file "/etc/mtab". These days, the kernel exports
868 the list of currently mounted partitions in "/proc/mounts", rendering
869 the old mtab file obsolete. (In modern systems, /etc/mtab should be
870 a symlink to /proc/mounts.)
872 The only reason to have mount maintain an /etc/mtab file itself is if
873 your stripped-down embedded system does not have a /proc directory.
874 If you must use this, keep in mind it's inherently brittle (for
875 example a mount under chroot won't update it), can't handle modern
876 features like separate per-process filesystem namespaces, requires
877 that your /etc directory be writeable, tends to get easily confused
878 by --bind or --move mounts, won't update if you rename a directory
879 that contains a mount point, and so on. (In brief: avoid.)
881 About the only reason to use this is if you've removed /proc from