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://developer.intel.com.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--test filename   don't write to NVRAM, write to filename-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 neededTypical usage:
1) Root can use it to display the current Boot Manager settings.[root@localhost ~]# efibootmgrBootCurrent: 0004BootNext: 0003BootOrder: 0004,0000,0001,0002,0003Timeout: 30 secondsBoot0000* Diskette Drive(device:0)Boot0001* CD-ROM Drive(device:FF) Boot0002* Hard Drive(Device:80)/HD(Part1,Sig00112233)   Boot0003* PXE Boot: MAC(00D0B7C15D91)               Boot0004* LinuxThis shows:BootCurrent - the boot entry used to start the currently runningsystem.BootOrder - the boot order as would appear in the boot manager.  Theboot manager tries to boot the first active entry on this list.  Ifunsuccessful, 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 theboot manager after first use.  This allows you to change the next bootbehavior without changing BootOrder.Timeout - the time in seconds between when the boot manager appearson the screen until when it automatically chooses the startup valuefrom BootNext or BootOrder.Five boot entries (0000 - 0004), the active/inactive flag (* meansactive), 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 topof the boot order list.  Options may be passed to modify thedefault behavior.  The default OS Loader is elilo.efi.3) A system administrator wants to change the boot order.  She wouldcall 'efibootmgr -o 3,4' to specify PXE boot first, then Linuxboot.4) A system administrator wants to change the boot order for the nextboot only.  She would call 'efibootmgr -n 4' to specify that theLinux entry be taken on next boot.5) A system administrator wants to delete the Linux boot option fromthe menu.  'efibootmgr -b 4 -B' deletes entry 4 and removes itfrom BootOrder.6) A system administrator wants to create a boot option to networkboot (PXE).  Unfortunately, this requires knowing a little moreinformation about your system than can be easily found byefibootmgr, so you've got to pass additional information - the ACPIHID and UID values.  These can generally be found by using the EFIBoot Manager (in the EFI environment) to create a network bootentry, then using efibootmgr to print it verbosely.  Here's one example:Boot003* Acpi(PNP0A03,0)/PCI(5|0)/Mac(00D0B7F9F510) \ACPI(a0341d0,0)PCI(0,5)MAC(00d0b7f9f510,0)In this case, the ACPI HID is "0A0341d0" and the UID is "0".For the zx2000 gigE, the HID is "222F" and the UID is "500".For the rx2000 gigE, the HID is "0002" and the UID is "100".You create the boot entry with:'efibootmgr -c -i eth0 -H 222F -U 500 -L netboot'Many other uses may be found.Please direct any bugs, features, patches, etc. to Matt Domsch
.