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Thread: efibootmgr questions

  1. #1
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    efibootmgr questions

    Please read instructions carefully and try to answer ( my ) questions only.

    If you have to support your answer with references to manual, try to be specific.
    ( See footnote #4 )






    Assuming the efibootmgr output came from UEFI firmware “boot sequence “.
    Statement : “boot” devices are identified by hardware and multi entries “ubuntu”.
    Questions:
    1.What are the entries called “ubuntu”? Definition ?
    2. Where did they come from / generated by whom ?
    3. If I disable the entry “ubuntu” and reboot, will it get regenerated ?

    If so – how do I test my modifications ?

    Code:
    a@a-desktop:~$ efibootmgr


    Code:
     BootCurrent: 0000
     Timeout: 1 seconds
     BootOrder: 0000,0007,0011,0006,0004,0008,0009,000A,000B,000C,000D,000E,000F,0010
     Boot0000* ubuntu
     Boot0004* USB  
     Boot0006* Hard Drive  
     Boot0007* ubuntu
     Boot0008* UEFI: Seagate BUP Ultra Touch 0004
     Boot0009* UEFI: Seagate BUP Ultra Touch 0004
     Boot000A* UEFI: Seagate BUP Ultra Touch 0004
     Boot000B* UEFI: Seagate
     Boot000C* UEFI: Seagate
     Boot000D* UEFI: Seagate
     Boot000E* UEFI: Seagate
     Boot000F* UEFI: Seagate
     Boot0010* UEFI: Seagate
     Boot0011* ubuntu
     a@a-desktop:~$

    FOOTNOTES ( some are dupes )
    When answering a question please:

    • Read the question carefully.
    • Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
    • If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
    • Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

    Let's work to help developers, not make them feel stupid.

  2. #2
    Join Date
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    Re: efibootmgr questions

    If you add the -v option to the efibootmgr command, it will show differences between the 'ubuntu' entries. Then repost.

    Like so:
    Code:
    [dmn@Sydney ~]$ sudo efibootmgr -v
    [sudo] password for dmn: 
    BootCurrent: 0001
    Timeout: 1 seconds
    BootOrder: 0001,0000,0003,000F,0025,0028,0002
    Boot0000* ubuntu	HD(1,GPT,78311638-4a51-458a-96e7-eff4a5629010,0x800,0x28000)/File(\EFI\UBUNTU\SHIMX64.EFI)
    Boot0001* manjaro	HD(1,GPT,65e53d74-b000-4f9e-9d58-c45398bf1083,0x800,0x32000)/File(\EFI\manjaro\grubx64.efi)
    Boot0002* ubuntu	HD(1,GPT,78311638-4a51-458a-96e7-eff4a5629010,0x800,0x28000)/File(\EFI\UBUNTU\GRUBX64.EFI)..BO
    Boot0003* UEFI OS	HD(1,GPT,78311638-4a51-458a-96e7-eff4a5629010,0x800,0x28000)/File(\EFI\BOOT\BOOTX64.EFI)..BO
    Boot000F* Fedora	HD(1,GPT,78311638-4a51-458a-96e7-eff4a5629010,0x800,0x28000)/File(\EFI\FEDORA\SHIMX64.EFI)
    Boot0025* UEFI OS	PciRoot(0x0)/Pci(0x1f,0x2)/Sata(4,65535,0)/HD(1,GPT,78311638-4a51-458a-96e7-eff4a5629010,0x800,0x28000)..BO
    Boot0028* UEFI OS	PciRoot(0x0)/Pci(0x1f,0x2)/Sata(4,65535,0)/HD(1,GPT,78311638-4a51-458a-96e7-eff4a5629010,0x800,0x28000)..BO
    They direct the UEFI firmware where to find the boot loader for each entry, and in what order to try the entries.

  3. #3
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    Re: efibootmgr questions

    I already know what they are.

    How does that answer my questions ?

    Is that where "ubuntu" came from ?



    Code:
    a@a-desktop:~$ efibootmgr -v
    BootCurrent: 0000
    Timeout: 1 seconds
    BootOrder: 0000,0007,0011,0006,0004,0008,0009,000A,000B,000C,000D,000E,000F,0010
    Boot0000* ubuntu    HD(2,GPT,44c98307-eb14-4cd8-ab7e-3138193729a1,0x100800,0x100800)/File(\EFI\ubuntu\shimx64.efi)
    Boot0004* USB     BBS(USB,,0x0)..GO..NO........].e.M. .B.a.y. .R.e.a.d.e.r. .1...0.0....................A...................................$..Gd-.;.A..MQ..L.9.2.0.3.1.1.1........BO..NO........e.e.M. .B.a.y. .R.e.a.d.e.r. .1...0.1....................A...........................................$..Gd-.;.A..MQ..L.9.2.0.3.1.1.1........BO..NO........e.e.M. .B.a.y. .R.e.a.d.e.r. .1...0.2....................A...........................................$..Gd-.;.A..MQ..L.9.2.0.3.1.1.1........BO..NO........i.S.e.a.g.a.t.e. .B.U.P. .U.l.t.r.a. .T.o.u.c.h. .0.0.0.4....................A.............................6..Gd-.;.A..MQ..L.0.0.0.0.0.0.0.0.N.A.B.1.3.3.H.H........BO..NO{.......Y.S.e.a.g.a.t.e....................A.............................&..Gd-.;.A..MQ..L.N.A.8.3.3.B.D.C........BO..NO........e.e.M. .B.a.y. .R.e.a.d.e.r. .1...0.3....................A...........................................$..Gd-.;.A..MQ..L.9.2.0.3.1.1.1........BO..NO........m.M.a.x.t.o.r. .O.n.e.T.o.u.c.h. .0.1.2.5....................A............................................Gd-.;.A..MQ..L.2.H.A.2.0.1.P.F. . . . ........BO
    Boot0006* Hard Drive     BBS(HD,,0x0)..GO..NO........u.W.D.C. .W.D.5.0.0.0.A.A.K.X.-.0.0.E.R.M.A.0....................A.................................>..Gd-.;.A..MQ..L. . . . .W. .-.D.C.W.2.C.W.E.4.9.5.7.9.3........BO..NO........o.W.D.C. .W.D.5.0.0.0.B.E.V.T.-.6.0.Z.A.T.0....................A...........................>..Gd-.;.A..MQ..L. . . . .W. .-.D.X.W.Y.N.8.0.C.K.5.M.9.1........BO..NO........o.W.D.C. .W.D.5.0.0.0.A.A.K.S.-.7.5.V.0.A.0....................A...........................>..Gd-.;.A..MQ..L. . . . .W. .-.D.C.W.W.A.8.F.5.3.6.8.8.8........BO..NO........u.S.T.3.3.2.0.4.1.8.A.S....................A.................................>..Gd-.;.A..MQ..L. . . . . . . . . . . . .V.6.P.M.D.L.P.Z........BO
    Boot0007* ubuntu    HD(1,GPT,db6b86b5-a4cc-4395-a80a-f2a4e652586a,0x800,0x100000)/File(\EFI\ubuntu\grubx64.efi)..BO
    Boot0008* UEFI: Seagate BUP Ultra Touch 0004    PciRoot(0x0)/Pci(0x1d,0x0)/USB(1,0)/USB(3,0)/HD(1,GPT,7149cebc-a872-4fa7-bf45-e75ea1672895,0xffff,0xefff1)..BO
    Boot0009* UEFI: Seagate BUP Ultra Touch 0004    PciRoot(0x0)/Pci(0x1d,0x0)/USB(1,0)/USB(3,0)/HD(10,GPT,66537b42-4255-4eef-886f-7f0d54024f1f,0x803c8000,0x39fbc000)..BO
    Boot000A* UEFI: Seagate BUP Ultra Touch 0004    PciRoot(0x0)/Pci(0x1d,0x0)/USB(1,0)/USB(3,0)/HD(12,GPT,eaa6938b-2fda-41b8-a307-6eaa95e594e4,0xba384000,0x3a98000)..BO
    Boot000B* UEFI: Seagate    PciRoot(0x0)/Pci(0x1d,0x0)/USB(1,0)/USB(4,0)/HD(1,MBR,0x4294967229,0x3f,0x33dccfc1)..BO
    Boot000C* UEFI: Seagate    PciRoot(0x0)/Pci(0x1d,0x0)/USB(1,0)/USB(4,0)/HD(2,MBR,0x4294967229,0x3605f800,0xf5aec000)/HD(1,MBR,0x0,0x36060000,0x4e2f800)..BO
    Boot000D* UEFI: Seagate    PciRoot(0x0)/Pci(0x1d,0x0)/USB(1,0)/USB(4,0)/HD(2,MBR,0x4294967229,0x3605f800,0xf5aec000)/HD(2,MBR,0x0,0x3ae90000,0x7b64000)..BO
    Boot000E* UEFI: Seagate    PciRoot(0x0)/Pci(0x1d,0x0)/USB(1,0)/USB(4,0)/HD(2,MBR,0x4294967229,0x3605f800,0xf5aec000)/HD(3,MBR,0x0,0x429f4800,0xc350000)..BO
    Boot000F* UEFI: Seagate    PciRoot(0x0)/Pci(0x1d,0x0)/USB(1,0)/USB(4,0)/HD(2,MBR,0x4294967229,0x3605f800,0xf5aec000)/HD(4,MBR,0x0,0x673e6800,0xd206800)..BO
    Boot0010* UEFI: Seagate    PciRoot(0x0)/Pci(0x1d,0x0)/USB(1,0)/USB(4,0)/HD(2,MBR,0x4294967229,0x3605f800,0xf5aec000)/HD(13,MBR,0x0,0xbe1a0800,0x100000)..BO
    Boot0011* ubuntu    HD(1,GPT,4f929080-5b02-4d52-a717-efffff17ed13,0x800,0x100000)/File(\EFI\ubuntu\grubx64.efi)..BO
    a@a-desktop:~$

  4. #4
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    Re: efibootmgr questions

    2) Where do they come from?
    They are made by the installer of the OS during installation.
    3) Will they regenerate if disabled?
    I don't know if it's possible to 'disable' one of these entries, but if you remove it, it will not regenerate when you reboot.

  5. #5
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    Re: efibootmgr questions

    Entry is created by the install of grub either seperately or by installing Ubuntu or other Linux distribution.
    Grub uses efibootmgr to create UEFI entry, and add files into ESP based on your install, partitions, UUIDs, GUIDs, etc.

    I have this from some log of grub install:
    Code:
    grub-install: info: Registering with EFI: distributor = `ubuntu', path = `EFIubuntushimx64.efi', ESP at hostdisk//dev/sda,gpt2.
    grub-install: info: executing efibootmgr --version </dev/null >/dev/null.
    grub-install: info: executing modprobe -q efivars.
    grub-install: info: executing efibootmgr -b 0003 -B.
    grub-install: info: executing efibootmgr -c -d /dev/sda -p 2 -w -L ubuntu -l EFIubuntushimx64.efi.
    See also, I know you do not like to read details, but this is how the entries are created or changed:
    man efibootmgr

    You can reinstall the ubuntu entry into UEFI to boot a specify Ubuntu.
    Code:
    sudo efibootmgr -c  -l \EFI\ubuntu\shimx64.efi -L "Ubuntu" -d /dev/sdX -p Y
    sdX is drive, Y is efi partition default is sda and first partition, so only required if not sda1
    sudo efibootmgr -c -g  -w -L "ubuntu" -l '\EFI\ubuntu\shimx64.efi' -d /dev/sda -p 1
    I believe some UEFI will re-recreate a Windows entry as that is the default with most systems.
    But it does not know what else you have and does not look for other installs. That is up to you.
    UEFI also deletes or changes entries if you physically remove a drive.

    UEFI entry for external devices is always /EFI/Boot/bootx64.efi for Windows, Ubuntu or other systems.
    Of course then bootx64.efi is unique on that installer for that system.
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  6. #6
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    Re: efibootmgr questions

    2) Where do they come from?
    They are made by the installer of the OS during installation.
    Close but no cigars.

    How about this

    The "ubuntu" entries are extracted from EFI (boot) partitions created by OS installer.

    Consequently "Ubuntu" - with capital "U" is a first entry in "grub" menu.


    (And the missing link between "ubuntu" and "grub" is still missing.)


    ( The other entries clearly points to BIOS MBR partitions )


    My question is poorly worded.

    Here is my original assumption

    Assuming the efibootmgr output came from UEFI firmware “boot sequence “.


    The identical sequence in displayed in "UEFI setup" , and it can be activated by different function keys.
    It can be manually changed or deleted "in UEFI setup" (firmware) PRIOR to system displaying grub menu.
    When modified or deleted in its entirety it will be restored NEXT time "UEFI setup " is run - on "reboot".
    It will be "automatically " ( per manual) reinitialized IF the BOOT process cannot be started - BY UEFI ,
    This is all well before ":grub menu" is displayed.


    Consider the above - removing "ubuntu" entry using efibootmgr
    1. does it remove the access to EFI partition or just instruct the efibootmgr to ignore the "removed " entry ?

    Little risky to "just try it " .

  7. #7
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    Re: efibootmgr questions

    You only boot in UEFI mode from the ubuntu entry.
    Unless your other entries are BIOS (which they cannot be), you would not be able to boot.
    Grub only can boot other installs in same boot mode, so all entries in grub menu are from same boot mode.

    UEFI set up is not run on reboot, only on install and repair, either Boot-Repair, or manually with efibootmgr from live installer.

    If you have all those installs, this will be a long report, but it shows details on UEFI entries, ESP and every grub you have. And if you follow GUID to ESP & UUID from ESP into install it shows which install is bootinge. And each grub menu will show all the other installs it can boot.

    Lets see details, use ppa version with your live installer (2nd option) or any working install, not Boot-Repair ISO:
    Please copy & paste the pastebin link to the Boot-info summary report ( do not post report), do not run the auto fix till reviewed.
    https://help.ubuntu.com/community/Boot-Repair
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  8. #8
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    Re: efibootmgr questions

    UEFI set up is not run on reboot, only on install and repair, either Boot-Repair, or manually with efibootmgr from live installer.

    So why UEFI MAINTAINS "boot sequence" if it does not run it ?
    How does UEFI option setting tres after preset number of failures (max 3) to run another "boot sequence"?
    BTW - as I already mentioned - MBR / BIOS sequences are included in " boot sequence" and thy work as expected when manually selected.
    .


    Please explain / describe HOW UEFI , NOT BIOS !, system gets from "power up" to display "grub" menu.

    Here is how it worked some 40 years ago - terminology will be different
    "Power detect" hardware applies , after delay, stable power to CPU
    CPU "process counter" is set to "all zeroes".
    "process counter" is manually set to ROM "starting address"
    ROM firmware runs FIRST program , in my ancient case - read holes in "boot" paper tape...

    This was called "booting the system" - no BIOS, UEFI, grub , OS...



    When answering a question please:



    1. Read the question carefully and try to answer "the question" not to explain how the world was created. .
    2. Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
    3. If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
    4. Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

    Let's work to help, not to make the original poster feel stupid.

  9. #9
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    Re: efibootmgr questions

    I'm afraid I still don't know what you are trying to achieve.
    Some time back I suggested trying Grub Customiser to gain some forensic insights
    into this confusing world but you asked why? Below answers why.

    grub-customizer.png

    Quote Grub Customiser is a graphical interface to configure the grub2/burg settings

    But as I wrote I now prefer to use rEFInd as my loader/gui (in addition to above entries)
    on a multi boot desktop.

    [P.S] Why do you find it necessary to pose the same questions in different threads?

    https://ubuntuforums.org/showthread.php?t=2452655
    Last edited by dragonfly41; 4 Weeks Ago at 06:17 PM. Reason: duplicate threads

  10. #10
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    Re: efibootmgr questions

    REPORT
    I install Boot_Repair.
    Since I do not read manuals I missed that part of INSTALL was actually to RUN the tool.
    It made me nervous, but I survived,

    It is pretty "one size fits all " tool and give more than plenty info about MY messy system.

    On first glance it did not uncover anything I did not already knew,

    Its ONLY recommendation was to ENABLE BIOS due to some Windows XP artifacts.
    I no longer use that.

    It did not add any new relations between boot / configuration files.
    Nor answered why my grub menu times out after 30 seconds - abandoned subject of another post.
    Last edited by wildmanne39; 4 Weeks Ago at 06:45 PM. Reason: Corrected spelling of Windows

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