efibootmgr development tree
C Groff Makefile
Latest commit 3466fd0 Jan 6, 2017 @steve-mcintyre steve-mcintyre committed with vathpela Don't use -fshort-wchar when building (#63)
It's not needed and is causing build failures with gcc 6. Closes
Debian bug #849651

Signed-off-by: Steve McIntyre <steve@einval.com>

README.md

This is efibootmgr, a Linux user-space application to modify the Intel Extensible Firmware Interface (EFI) Boot Manager. This application can create and destroy boot entries, change the boot order, change the next running boot option, and more.

Details on the EFI Boot Manager are available from the EFI Specification, v1.02 or above, available from http://www.uefi.org.

Note: efibootmgr requires that the kernel module efivars be loaded prior to use. modprobe efivars should do the trick.

usage: efibootmgr [options]
    -a | --active         sets bootnum active
    -A | --inactive       sets bootnum inactive
    -b | --bootnum XXXX   modify BootXXXX (hex)
    -B | --delete-bootnum delete bootnum (hex)
    -c | --create         create new variable bootnum and add to bootorder
    -d | --disk disk      (defaults to /dev/sda) containing loader
    -e | --edd [1|3|-1]   force EDD 1.0 or 3.0 creation variables, or guess
    -E | --device num     EDD 1.0 device number (defaults to 0x80)
    -g | --gpt            force disk w/ invalid PMBR to be treated as GPT 
    -H | --acpi_hid XXXX  set the ACPI HID (used with -i)
    -i | --iface name     create a netboot entry for the named interface
    -l | --loader name    (defaults to \elilo.efi)
    -L | --label label    Boot manager display label (defaults to "Linux")
    -n | --bootnext XXXX  set BootNext to XXXX (hex)
    -N | --delete-bootnext delete BootNext
    -o | --bootorder XXXX,YYYY,ZZZZ,...     explicitly set BootOrder (hex)
    -O | --delete-bootorder delete BootOrder
    -p | --part part       (defaults to 1) containing loader
    -q | --quiet           be quiet
    -t | --timeout seconds   Boot manager timeout
    -T | --delete-timeout    delete Timeout value
    -u | --unicode | --UCS-2  pass extra args as UCS-2 (default is ASCII)
    -U | --acpi_uid XXXX    set the ACPI UID (used with -i)
    -v | --verbose         print additional information
    -V | --version         return version and exit
    -w | --write-signature  write unique sig to MBR if needed
    -@ | --append-binary-args   append extra variable args from
                              file (use - to read from stdin).

Typical usage: 1) Root can use it to display the current Boot Manager settings.

[root@localhost ~]# efibootmgr
BootCurrent: 0004
BootNext: 0003
BootOrder: 0004,0000,0001,0002,0003
Timeout: 30 seconds
Boot0000* Diskette Drive(device:0)
Boot0001* CD-ROM Drive(device:FF) 
Boot0002* Hard Drive(Device:80)/HD(Part1,Sig00112233)   
Boot0003* PXE Boot: MAC(00D0B7C15D91)               
Boot0004* Linux

This shows:

BootCurrent - the boot entry used to start the currently running system.

BootOrder - the boot order as would appear in the boot manager. The boot manager tries to boot the first active entry on this list. If unsuccessful, it tries the next entry, and so on.

BootNext - the boot entry which is scheduled to be run on next boot. This superceeds BootOrder for one boot only, and is deleted by the boot manager after first use. This allows you to change the next boot behavior without changing BootOrder.

Timeout - the time in seconds between when the boot manager appears on the screen until when it automatically chooses the startup value from BootNext or BootOrder.

Five boot entries (0000 - 0004), the active/inactive flag (* means active), and the name displayed on the screen.

2) An OS installer would call efibootmgr -c. This assumes that /boot/efi is your EFI System Partition, and is mounted at /dev/sda1. This creates a new boot option, called "Linux", and puts it at the top of the boot order list. Options may be passed to modify the default behavior. The default OS Loader is elilo.efi.

3) A system administrator wants to change the boot order. She would call efibootmgr -o 3,4 to specify PXE boot first, then Linux boot.

4) A system administrator wants to change the boot order for the next boot only. She would call efibootmgr -n 4 to specify that the Linux entry be taken on next boot.

5) A system administrator wants to delete the Linux boot option from the menu. efibootmgr -b 4 -B deletes entry 4 and removes it from BootOrder.

6) A system administrator wants to create a boot option to network boot (PXE). You create the boot entry with: efibootmgr -c -i eth0 -L netboot

Many other uses may be found.

Please direct any bugs, features, patches, etc. to Peter Jones, https://github.com/rhinstaller/efibootmgr .