===================================================================================
Depuis LINUX/STELLARMATE X
===================================================================================
Par  defaut on boot Stellarmate

https://doc.ubuntu-fr.org/efibootmgr
# efibootmgr -v
BootCurrent: 000B
Timeout: 2 seconds
BootOrder: 000B,0001,0009,000A,0000,0004
Boot0000* Windows Boot Manager	HD(1,GPT,384fb274-adb0-4ff4-9b9f-64a4228e82e9,0x800,0x32000)/File(\EFI\MICROSOFT\BOOT\BOOTMGFW.EFI)WINDOWS.........x...B.C.D.O.B.J.E.C.T.=.{.9.d.e.a.8.6.2.c.-.5.c.d.d.-.4.e.7.0.-.a.c.c.1.-.f.3.2.b.3.4.4.d.4.7.9.5.}....................
Boot0001* Windows Boot Manager	HD(1,GPT,384fb274-adb0-4ff4-9b9f-64a4228e82e9,0x800,0x32000)/File(\EFI\OEM\BOOT\BOOTMGFW.EFI)
Boot0004* UEFI: Built-in EFI Shell	VenMedia(5023b95c-db26-429b-a648-bd47664c8012)..BO
Boot0009* UEFI: PXE IPv4 Realtek PCIe GBE Family Controller	PciRoot(0x0)/Pci(0x1c,0x0)/Pci(0x0,0x0)/MAC(0039ced22322,0)/IPv4(0.0.0.00.0.0.0,0,0)..BO
Boot000A* UEFI: PXE IPv6 Realtek PCIe GBE Family Controller	PciRoot(0x0)/Pci(0x1c,0x0)/Pci(0x0,0x0)/MAC(0039ced22322,0)/IPv6([::]:<->[::]:,0,0)..BO
Boot000B* ubuntu	HD(1,MBR,0x38fa9f77,0x800,0x100000)/File(\EFI\UBUNTU\SHIMX64.EFI)..BO

On BootCurrent: 000B => Boot000B* ubuntu	HD(1,MBR,0x38fa9f77,0x800,0x100000)/File(\EFI\UBUNTU\SHIMX64.EFI)..BO

pour Booter Windows en priorité
Si vous souhaitez ou vous devez modifier l'ordre d'amorçage des entrées UEFI , il suffit dans la commande suivante, 
de classer de la première à la dernière séparée d'une virgule les valeurs hexadécimales de chaque entrée UEFI disponible.

sudo efibootmgr -o 0000,0001,000B,0004,0009,000A
BootCurrent: 000B
Timeout: 2 seconds
BootOrder: 0000,0001,000B,0004,0009,000A
Boot0000* Windows Boot Manager	HD(1,GPT,384fb274-adb0-4ff4-9b9f-64a4228e82e9,0x800,0x32000)/File(\EFI\MICROSOFT\BOOT\BOOTMGFW.EFI)WINDOWS.........x...B.C.D.O.B.J.E.C.T.=.{.9.d.e.a.8.6.2.c.-.5.c.d.d.-.4.e.7.0.-.a.c.c.1.-.f.3.2.b.3.4.4.d.4.7.9.5.}....................
Boot0001* Windows Boot Manager	HD(1,GPT,384fb274-adb0-4ff4-9b9f-64a4228e82e9,0x800,0x32000)/File(\EFI\OEM\BOOT\BOOTMGFW.EFI)
Boot0004* UEFI: Built-in EFI Shell	VenMedia(5023b95c-db26-429b-a648-bd47664c8012)..BO
Boot0009* UEFI: PXE IPv4 Realtek PCIe GBE Family Controller	PciRoot(0x0)/Pci(0x1c,0x0)/Pci(0x0,0x0)/MAC(0039ced22322,0)/IPv4(0.0.0.00.0.0.0,0,0)..BO
Boot000A* UEFI: PXE IPv6 Realtek PCIe GBE Family Controller	PciRoot(0x0)/Pci(0x1c,0x0)/Pci(0x0,0x0)/MAC(0039ced22322,0)/IPv6([::]:<->[::]:,0,0)..BO
Boot000B* ubuntu	HD(1,MBR,0x38fa9f77,0x800,0x100000)/File(\EFI\UBUNTU\SHIMX64.EFI)..BO

apres  reboot on boot windows et l'ordre de boot a changé  dans le BIOS


===================================================================================
Depuis WINDOWS
===================================================================================
https://stackoverflow.com/questions/44919190/windows-equivalent-to-efibootmgr

Also, for all the commands an elevated command prompt should be used, i.e. run cmd.exe (not PowerShell!) with administrator rights!

If a Linux boot loader is already configured, the sequence can be changed with bcdedit /enum firmware should list it. 
Imporant is only the GUID of the boot loader object listed with the Linux boot loader, i.e. a string looking like {01234567-89AB-CDEF-0123-456789ABCDEF}, 
and replace {<GUID>} in the following examples with your actual GUID.

Any firmware boot loader can be set as the default EFI boot option with bcdedit /set {fwbootmgr} default {<GUID>}.

To set a EFI boot loader entry as the first boot item in the list, bcdedit /set {fwbootmgr} displayorder {<GUID>} /addfirst can be used.

C:\Users\Pollux>bcdedit

Gestionnaire de démarrage Windows
---------------------------------
identificateur          {bootmgr}
device                  partition=\Device\HarddiskVolume1
path                    \EFI\MICROSOFT\BOOT\BOOTMGFW.EFI
description             Windows Boot Manager
locale                  fr-FR
inherit                 {globalsettings}
default                 {current}
resumeobject            {b1575a45-d98b-11ed-be64-0039ced22322}
displayorder            {current}
toolsdisplayorder       {memdiag}
timeout                 30

Chargeur de démarrage Windows
-----------------------------
identificateur          {current}
device                  partition=C:
path                    \WINDOWS\system32\winload.efi
description             Windows 11
locale                  fr-FR
inherit                 {bootloadersettings}
recoverysequence        {0115bdcf-d986-11ed-a18d-afe458fdd33d}
displaymessageoverride  Recovery
recoveryenabled         No
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=C:
systemroot              \WINDOWS
resumeobject            {b1575a45-d98b-11ed-be64-0039ced22322}
nx                      OptIn
bootmenupolicy          Standard
bootstatuspolicy        IgnoreAllFailures

C:\Users\Pollux>bcdedit /enum firmware

Gestionnaire de démarrage du microprogramme
-------------------------------------------
identificateur          {fwbootmgr}
displayorder            {bootmgr}
                        {9a040d99-ddd6-11ed-a197-806e6f6e6963}
                        {92727642-da03-11ed-8d07-806e6f6e6963}
                        {80ee2960-d98d-11ed-a18c-806e6f6e6963}
                        {80ee2961-d98d-11ed-a18c-806e6f6e6963}
                        {80ee2962-d98d-11ed-a18c-806e6f6e6963}
timeout                 2

Gestionnaire de démarrage Windows
---------------------------------
identificateur          {bootmgr}
device                  partition=\Device\HarddiskVolume1
path                    \EFI\MICROSOFT\BOOT\BOOTMGFW.EFI
description             Windows Boot Manager
locale                  fr-FR
inherit                 {globalsettings}
default                 {current}
resumeobject            {b1575a45-d98b-11ed-be64-0039ced22322}
displayorder            {current}
toolsdisplayorder       {memdiag}
timeout                 30

Application logicielle (101fffff)
--------------------------------
identificateur          {80ee2960-d98d-11ed-a18c-806e6f6e6963}
description             UEFI: Built-in EFI Shell

Application logicielle (101fffff)
--------------------------------
identificateur          {80ee2961-d98d-11ed-a18c-806e6f6e6963}
description             UEFI: PXE IPv4 Realtek PCIe GBE Family Controller

Application logicielle (101fffff)
--------------------------------
identificateur          {80ee2962-d98d-11ed-a18c-806e6f6e6963}
description             UEFI: PXE IPv6 Realtek PCIe GBE Family Controller

Application logicielle (101fffff)
--------------------------------
identificateur          {92727642-da03-11ed-8d07-806e6f6e6963} <====== UBUNTU
device                  partition=\Device\HarddiskVolume6
path                    \EFI\UBUNTU\SHIMX64.EFI
description             ubuntu

Application logicielle (101fffff)
--------------------------------
identificateur          {9a040d99-ddd6-11ed-a197-806e6f6e6963}
device                  partition=\Device\HarddiskVolume1
path                    \EFI\OEM\BOOT\BOOTMGFW.EFI
description             Windows Boot Manager

C:\Users\Pollux>bcdedit /set {fwbootmgr} displayorder {92727642-da03-11ed-8d07-806e6f6e6963} /addfirst
L’opération a réussi.
C:\Users\Pollux>bcdedit /enum firmware

Gestionnaire de démarrage du microprogramme
-------------------------------------------
identificateur          {fwbootmgr}
displayorder            {92727642-da03-11ed-8d07-806e6f6e6963}
                        {bootmgr}
                        {9a040d99-ddd6-11ed-a197-806e6f6e6963}
                        {80ee2960-d98d-11ed-a18c-806e6f6e6963}
                        {80ee2961-d98d-11ed-a18c-806e6f6e6963}
                        {80ee2962-d98d-11ed-a18c-806e6f6e6963}
timeout                 2

Gestionnaire de démarrage Windows
---------------------------------
identificateur          {bootmgr}
device                  partition=\Device\HarddiskVolume1
path                    \EFI\MICROSOFT\BOOT\BOOTMGFW.EFI
description             Windows Boot Manager
locale                  fr-FR
inherit                 {globalsettings}
default                 {current}
resumeobject            {b1575a45-d98b-11ed-be64-0039ced22322}
displayorder            {current}
toolsdisplayorder       {memdiag}
timeout                 30

Application logicielle (101fffff)
--------------------------------
identificateur          {80ee2960-d98d-11ed-a18c-806e6f6e6963}
description             UEFI: Built-in EFI Shell

Application logicielle (101fffff)
--------------------------------
identificateur          {80ee2961-d98d-11ed-a18c-806e6f6e6963}
description             UEFI: PXE IPv4 Realtek PCIe GBE Family Controller

Application logicielle (101fffff)
--------------------------------
identificateur          {80ee2962-d98d-11ed-a18c-806e6f6e6963}
description             UEFI: PXE IPv6 Realtek PCIe GBE Family Controller

Application logicielle (101fffff)
--------------------------------
identificateur          {92727642-da03-11ed-8d07-806e6f6e6963}
device                  partition=\Device\HarddiskVolume6
path                    \EFI\UBUNTU\SHIMX64.EFI
description             ubuntu

Application logicielle (101fffff)
--------------------------------
identificateur          {9a040d99-ddd6-11ed-a197-806e6f6e6963}
device                  partition=\Device\HarddiskVolume1
path                    \EFI\OEM\BOOT\BOOTMGFW.EFI
description             Windows Boot Manager

C:\Users\Pollux>