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    VM UUID via dmidecode does not match VM ID in xen-orchestra

    Scheduled Pinned Locked Moved Infrastructure as Code
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    • D Offline
      deefdragon @Cyrille
      last edited by deefdragon

      @Cyrille Genuinly no idea unfortunately. The only thing I can think that I've done is that the VMs are being loaded in from a template.

      I had to deploy new VMs through my terraform recently, and I AM still seeing an incorrect system UUID on those, so I can only guess its somehow the template?

      I am also seeing the serial number from DMIDECODE match the VM ID in xen orchestra as well still.

      CyrilleC 1 Reply Last reply Reply Quote 0
      • CyrilleC Offline
        Cyrille Vates 🪐 DevOps Team @deefdragon
        last edited by

        @deefdragon can you check if /sys/hypervisor/uuid matches your VMs UUID?

        D 1 Reply Last reply Reply Quote 0
        • D Offline
          deefdragon @Cyrille
          last edited by

          @Cyrille I am seeing /sys/hypervisor/uuid matching dmidecode's Serial Number matching VM ID in xen orchestra.

          dmidecode's UUID however is different from those three.

          D 1 Reply Last reply Reply Quote 1
          • D Offline
            dinhngtu Vates 🪐 XCP-ng Team @deefdragon
            last edited by dinhngtu

            @deefdragon All three values match for me with XCP-ng 8.3, Ubuntu 24.04 guests and kernel 6.8:

            $ sudo cat /sys/devices/virtual/dmi/id/product_serial
            adc9b6ba-d187-0844-13a6-5f1dc155bf6e
            $ sudo cat /sys/devices/virtual/dmi/id/product_uuid
            adc9b6ba-d187-0844-13a6-5f1dc155bf6e
            $ sudo cat /sys/hypervisor/uuid
            adc9b6ba-d187-0844-13a6-5f1dc155bf6e
            

            From your Github issue, it looks like a confusion in byte order between the System UUID (6a87cb0f-ca4c-ffa5-3ca2-fc398fb25eac) and the XCP-ng VM UUID (0fcb876a-4cca-a5ff-3ca2-fc398fb25eac).

            I'd check the guest kernel version first.

            D 1 Reply Last reply Reply Quote 0
            • D Offline
              deefdragon @dinhngtu
              last edited by deefdragon

              @dinhngtu

              Ah, I see the pattern now. That is bizarre.

              deef@k31-w-3bfbbe:~$ sudo cat /sys/devices/virtual/dmi/id/product_serial
              0b08f477-491a-a982-23c4-d224723624ea
              deef@k31-w-3bfbbe:~$ sudo cat /sys/devices/virtual/dmi/id/product_uuid
              77f4080b-1a49-82a9-23c4-d224723624ea
              deef@k31-w-3bfbbe:~$ sudo cat /sys/hypervisor/uuid
              0b08f477-491a-a982-23c4-d224723624ea
              

              Heres the output from a series of commands I ran to get the info of the worker. Seeing 6.8 and 24.04 myself.

              deef@k31-w-3bfbbe:~$ cat /etc/*-release
              DISTRIB_ID=Ubuntu
              DISTRIB_RELEASE=24.04
              DISTRIB_CODENAME=noble
              DISTRIB_DESCRIPTION="Ubuntu 24.04.2 LTS"
              PRETTY_NAME="Ubuntu 24.04.2 LTS"
              NAME="Ubuntu"
              VERSION_ID="24.04"
              VERSION="24.04.2 LTS (Noble Numbat)"
              VERSION_CODENAME=noble
              ID=ubuntu
              ID_LIKE=debian
              HOME_URL="https://www.ubuntu.com/"
              SUPPORT_URL="https://help.ubuntu.com/"
              BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
              PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
              UBUNTU_CODENAME=noble
              LOGO=ubuntu-logo
              
              deef@k31-w-3bfbbe:~$ lsb_release -a
              No LSB modules are available.
              Distributor ID:	Ubuntu
              Description:	Ubuntu 24.04.2 LTS
              Release:	24.04
              Codename:	noble
              
              deef@k31-w-3bfbbe:~$ hostnamectl
               Static hostname: k31-w-3bfbbe
                     Icon name: computer-vm
                       Chassis: vm 🖴
                    Machine ID: 9bae21fe1e10d9da92da72599fd7b4a3
                       Boot ID: 959ebf2dc51e403eaf00103d51e8397e
                Virtualization: xen
              Operating System: Ubuntu 24.04.2 LTS              
                        Kernel: Linux 6.8.0-64-generic
                  Architecture: x86-64
               Hardware Vendor: Xen
                Hardware Model: HVM domU
              Firmware Version: 4.17
                 Firmware Date: Tue 2025-05-13
                  Firmware Age: 2month 2w 3d
              
              deef@k31-w-3bfbbe:~$ uname -r
              6.8.0-64-generic
              
              

              LMK if there is anything else you want me to throw at it, or any other debug info you want me to get. I'm out of my depth when it comes to debugging this kind of thing.

              D 1 Reply Last reply Reply Quote 0
              • D Offline
                dinhngtu Vates 🪐 XCP-ng Team @deefdragon
                last edited by

                @deefdragon How about host Xen and XAPI versions? I'm on the bleeding edge, so this may have been fixed somewhere already.

                # unbuffer yum list installed | grep xen\\\|xapi
                mellanox-mlnxen.x86_64            5.9_0.5.5.0-2.1.xcpng8.3    @xcp:main/$releasever
                python2-xapi-storage.x86_64       24.19.2-1.10.xcpng8.3       @xcp-ng-testing
                xapi-core.x86_64                  25.6.0-1.10.xcpng8.3        @xcp-ng-incoming
                xapi-nbd.x86_64                   25.6.0-1.10.xcpng8.3        @xcp-ng-incoming
                xapi-rrd2csv.x86_64               25.6.0-1.10.xcpng8.3        @xcp-ng-incoming
                xapi-storage-script.x86_64        25.6.0-1.10.xcpng8.3        @xcp-ng-incoming
                xapi-tests.x86_64                 25.6.0-1.10.xcpng8.3        @xcp-ng-incoming
                xapi-xe.x86_64                    25.6.0-1.10.xcpng8.3        @xcp-ng-incoming
                xcp-ng-xapi-plugins.noarch        1.12.0-1.xcpng8.3           @xcp-ng-testing
                xen-crashdump-analyser.x86_64     2.6.1-1.xcpng8.3            @xcp:main/$releasever
                xen-dom0-libs.x86_64              4.17.5-15.2.xcpng8.3        @xcp-ng-incoming
                xen-dom0-tools.x86_64             4.17.5-15.2.xcpng8.3        @xcp-ng-incoming
                xen-hypervisor.x86_64             4.17.5-15.2.xcpng8.3        @xcp-ng-incoming
                xen-libs.x86_64                   4.17.5-15.2.xcpng8.3        @xcp-ng-incoming
                xen-tools.x86_64                  4.17.5-15.2.xcpng8.3        @xcp-ng-incoming
                xengt-userspace.noarch            4.0.0-1.xcpng8.3            @xcp:main/$releasever
                xenopsd.x86_64                    25.6.0-1.10.xcpng8.3        @xcp-ng-incoming
                xenopsd-cli.x86_64                25.6.0-1.10.xcpng8.3        @xcp-ng-incoming
                xenopsd-xc.x86_64                 25.6.0-1.10.xcpng8.3        @xcp-ng-incoming
                xenserver-dracut.noarch           10-2.xcpng8.3               @xcp:main/$releasever
                xenserver-hwdata.noarch           20240411-1.xcpng8.3         @xcp:main/$releasever
                xenserver-status-report.noarch    2.0.11-1.xcpng8.3           @xcp-ng-ci
                
                D 1 Reply Last reply Reply Quote 0
                • D Offline
                  deefdragon @dinhngtu
                  last edited by

                  @dinhngtu

                  Only difference looks to be xen-dom0 etc. on 4.17.5-13.1.xcpng8.3 vs your 4.17.5-15.2.xcpng8.3

                  # unbuffer yum list installed | grep xen\\\|xapi
                  mellanox-mlnxen.x86_64                   5.9_0.5.5.0-2.1.xcpng8.3         @xcp:main/$releasever
                  python2-xapi-storage.x86_64              24.19.2-1.10.xcpng8.3            @xcp-ng-updates      
                  xapi-core.x86_64                         25.6.0-1.5.xcpng8.3              @xcp-ng-updates      
                  xapi-nbd.x86_64                          25.6.0-1.5.xcpng8.3              @xcp-ng-updates      
                  xapi-rrd2csv.x86_64                      25.6.0-1.5.xcpng8.3              @xcp-ng-updates      
                  xapi-storage-script.x86_64               25.6.0-1.5.xcpng8.3              @xcp-ng-updates      
                  xapi-tests.x86_64                        25.6.0-1.5.xcpng8.3              @xcp-ng-updates      
                  xapi-xe.x86_64                           25.6.0-1.5.xcpng8.3              @xcp-ng-updates      
                  xcp-ng-xapi-plugins.noarch               1.12.0-1.xcpng8.3                @xcp-ng-updates      
                  xen-crashdump-analyser.x86_64            2.6.1-1.xcpng8.3                 @xcp:main/$releasever
                  xen-dom0-libs.x86_64                     4.17.5-13.1.xcpng8.3             @xcp-ng-updates      
                  xen-dom0-tools.x86_64                    4.17.5-13.1.xcpng8.3             @xcp-ng-updates      
                  xen-hypervisor.x86_64                    4.17.5-13.1.xcpng8.3             @xcp-ng-updates      
                  xen-libs.x86_64                          4.17.5-13.1.xcpng8.3             @xcp-ng-updates      
                  xen-tools.x86_64                         4.17.5-13.1.xcpng8.3             @xcp-ng-updates      
                  xengt-userspace.noarch                   4.0.0-1.xcpng8.3                 @xcp:main/$releasever
                  xenopsd.x86_64                           25.6.0-1.5.xcpng8.3              @xcp-ng-updates      
                  xenopsd-cli.x86_64                       25.6.0-1.5.xcpng8.3              @xcp-ng-updates      
                  xenopsd-xc.x86_64                        25.6.0-1.5.xcpng8.3              @xcp-ng-updates      
                  xenserver-dracut.noarch                  10-2.xcpng8.3                    @xcp:main/$releasever
                  xenserver-hwdata.noarch                  20240411-1.xcpng8.3              @xcp:main/$releasever
                  xenserver-status-report.noarch           2.0.11-1.xcpng8.3                @xcp-ng-updates      
                  
                  D 1 Reply Last reply Reply Quote 0
                  • D Offline
                    dinhngtu Vates 🪐 XCP-ng Team @deefdragon
                    last edited by

                    @deefdragon Your XAPI is also lagging behind (25.6.0-1.5 vs latest 25.6.0-1.9). Could you update your pool?

                    D 1 Reply Last reply Reply Quote 0
                    • TeddyAstieT Offline
                      TeddyAstie Vates 🪐 XCP-ng Team Xen Guru
                      last edited by

                      deef@k31-w-3bfbbe:~$ sudo cat /sys/devices/virtual/dmi/id/product_serial
                      0b08f477-491a-a982-23c4-d224723624ea
                      deef@k31-w-3bfbbe:~$ sudo cat /sys/devices/virtual/dmi/id/product_uuid
                      77f4080b-1a49-82a9-23c4-d224723624ea
                      deef@k31-w-3bfbbe:~$ sudo cat /sys/hypervisor/uuid
                      0b08f477-491a-a982-23c4-d224723624ea
                      

                      It looks like a endianness issue (0b08f477 vs 77f4080b).

                      1 Reply Last reply Reply Quote 0
                      • TeddyAstieT Offline
                        TeddyAstie Vates 🪐 XCP-ng Team Xen Guru
                        last edited by

                        @deefdragon can you provide us the output of dmidecode in the guest ?

                        1 Reply Last reply Reply Quote 0
                        • D Offline
                          deefdragon @dinhngtu
                          last edited by

                          @dinhngtu Updated through xo. These are the current values.

                          mellanox-mlnxen.x86_64               5.9_0.5.5.0-2.1.xcpng8.3       @xcp:main/$releasever
                          python2-xapi-storage.x86_64          24.19.2-1.10.xcpng8.3          @xcp-ng-updates      
                          xapi-core.x86_64                     25.6.0-1.9.xcpng8.3            @xcp-ng-updates      
                          xapi-nbd.x86_64                      25.6.0-1.9.xcpng8.3            @xcp-ng-updates      
                          xapi-rrd2csv.x86_64                  25.6.0-1.9.xcpng8.3            @xcp-ng-updates      
                          xapi-storage-script.x86_64           25.6.0-1.9.xcpng8.3            @xcp-ng-updates      
                          xapi-tests.x86_64                    25.6.0-1.9.xcpng8.3            @xcp-ng-updates      
                          xapi-xe.x86_64                       25.6.0-1.9.xcpng8.3            @xcp-ng-updates      
                          xcp-ng-xapi-plugins.noarch           1.12.0-1.xcpng8.3              @xcp-ng-updates      
                          xen-crashdump-analyser.x86_64        2.6.1-1.xcpng8.3               @xcp:main/$releasever
                          xen-dom0-libs.x86_64                 4.17.5-15.1.xcpng8.3           @xcp-ng-updates      
                          xen-dom0-tools.x86_64                4.17.5-15.1.xcpng8.3           @xcp-ng-updates      
                          xen-hypervisor.x86_64                4.17.5-15.1.xcpng8.3           @xcp-ng-updates      
                          xen-libs.x86_64                      4.17.5-15.1.xcpng8.3           @xcp-ng-updates      
                          xen-tools.x86_64                     4.17.5-15.1.xcpng8.3           @xcp-ng-updates      
                          xengt-userspace.noarch               4.0.0-1.xcpng8.3               @xcp:main/$releasever
                          xenopsd.x86_64                       25.6.0-1.9.xcpng8.3            @xcp-ng-updates      
                          xenopsd-cli.x86_64                   25.6.0-1.9.xcpng8.3            @xcp-ng-updates      
                          xenopsd-xc.x86_64                    25.6.0-1.9.xcpng8.3            @xcp-ng-updates      
                          xenserver-dracut.noarch              10-2.xcpng8.3                  @xcp:main/$releasever
                          xenserver-hwdata.noarch              20240411-1.xcpng8.3            @xcp:main/$releasever
                          xenserver-status-report.noarch       2.0.11-1.xcpng8.3              @xcp-ng-updates      
                          
                          

                          Gave one of the VMs a reboot and got the same result as previous.

                          Full DMI Decode as requested @TeddyAstie

                          # dmidecode
                          # dmidecode 3.5
                          Getting SMBIOS data from sysfs.
                          SMBIOS 2.8 present.
                          19 structures occupying 691 bytes.
                          Table at 0xEE6FC000.
                          
                          Handle 0x0000, DMI type 0, 24 bytes
                          BIOS Information
                          	Vendor: Xen
                          	Version: 4.17
                          	Release Date: 07/10/2025
                          	Address: 0xE8000
                          	Runtime Size: 96 kB
                          	ROM Size: 64 kB
                          	Characteristics:
                          		PCI is supported
                          		EDD is supported
                          		Targeted content distribution is supported
                          	BIOS Revision: 4.17
                          
                          Handle 0x0100, DMI type 1, 27 bytes
                          System Information
                          	Manufacturer: Xen
                          	Product Name: HVM domU
                          	Version: 4.17
                          	Serial Number: 0b08f477-491a-a982-23c4-d224723624ea
                          	UUID: 77f4080b-1a49-82a9-23c4-d224723624ea
                          	Wake-up Type: Power Switch
                          	SKU Number: Not Specified
                          	Family: Not Specified
                          
                          Handle 0x0300, DMI type 3, 21 bytes
                          Chassis Information
                          	Manufacturer: Xen
                          	Type: Other
                          	Lock: Not Present
                          	Version: Not Specified
                          	Serial Number: Not Specified
                          	Asset Tag: Not Specified
                          	Boot-up State: Safe
                          	Power Supply State: Safe
                          	Thermal State: Safe
                          	Security Status: Unknown
                          	OEM Information: 0x00000000
                          	Height: Unspecified
                          	Number Of Power Cords: Unspecified
                          	Contained Elements: 0
                          
                          Handle 0x0401, DMI type 4, 35 bytes
                          Processor Information
                          	Socket Designation: CPU 1
                          	Type: Central Processor
                          	Family: Other
                          	Manufacturer: Intel
                          	ID: F1 06 04 00 FF FB CB 0F
                          	Version: Not Specified
                          	Voltage: Unknown
                          	External Clock: Unknown
                          	Max Speed: 2100 MHz
                          	Current Speed: 2100 MHz
                          	Status: Populated, Enabled
                          	Upgrade: Other
                          	L1 Cache Handle: Not Provided
                          	L2 Cache Handle: Not Provided
                          	L3 Cache Handle: Not Provided
                          	Serial Number: Not Specified
                          	Asset Tag: Not Specified
                          	Part Number: Not Specified
                          
                          Handle 0x0402, DMI type 4, 35 bytes
                          Processor Information
                          	Socket Designation: CPU 2
                          	Type: Central Processor
                          	Family: Other
                          	Manufacturer: Intel
                          	ID: F1 06 04 00 FF FB CB 0F
                          	Version: Not Specified
                          	Voltage: Unknown
                          	External Clock: Unknown
                          	Max Speed: 2100 MHz
                          	Current Speed: 2100 MHz
                          	Status: Populated, Enabled
                          	Upgrade: Other
                          	L1 Cache Handle: Not Provided
                          	L2 Cache Handle: Not Provided
                          	L3 Cache Handle: Not Provided
                          	Serial Number: Not Specified
                          	Asset Tag: Not Specified
                          	Part Number: Not Specified
                          
                          Handle 0x0403, DMI type 4, 35 bytes
                          Processor Information
                          	Socket Designation: CPU 3
                          	Type: Central Processor
                          	Family: Other
                          	Manufacturer: Intel
                          	ID: F1 06 04 00 FF FB CB 0F
                          	Version: Not Specified
                          	Voltage: Unknown
                          	External Clock: Unknown
                          	Max Speed: 2100 MHz
                          	Current Speed: 2100 MHz
                          	Status: Populated, Enabled
                          	Upgrade: Other
                          	L1 Cache Handle: Not Provided
                          	L2 Cache Handle: Not Provided
                          	L3 Cache Handle: Not Provided
                          	Serial Number: Not Specified
                          	Asset Tag: Not Specified
                          	Part Number: Not Specified
                          
                          Handle 0x0404, DMI type 4, 35 bytes
                          Processor Information
                          	Socket Designation: CPU 4
                          	Type: Central Processor
                          	Family: Other
                          	Manufacturer: Intel
                          	ID: F1 06 04 00 FF FB CB 0F
                          	Version: Not Specified
                          	Voltage: Unknown
                          	External Clock: Unknown
                          	Max Speed: 2100 MHz
                          	Current Speed: 2100 MHz
                          	Status: Populated, Enabled
                          	Upgrade: Other
                          	L1 Cache Handle: Not Provided
                          	L2 Cache Handle: Not Provided
                          	L3 Cache Handle: Not Provided
                          	Serial Number: Not Specified
                          	Asset Tag: Not Specified
                          	Part Number: Not Specified
                          
                          Handle 0x0405, DMI type 4, 35 bytes
                          Processor Information
                          	Socket Designation: CPU 5
                          	Type: Central Processor
                          	Family: Other
                          	Manufacturer: Intel
                          	ID: F1 06 04 00 FF FB CB 0F
                          	Version: Not Specified
                          	Voltage: Unknown
                          	External Clock: Unknown
                          	Max Speed: 2100 MHz
                          	Current Speed: 2100 MHz
                          	Status: Populated, Enabled
                          	Upgrade: Other
                          	L1 Cache Handle: Not Provided
                          	L2 Cache Handle: Not Provided
                          	L3 Cache Handle: Not Provided
                          	Serial Number: Not Specified
                          	Asset Tag: Not Specified
                          	Part Number: Not Specified
                          
                          Handle 0x0406, DMI type 4, 35 bytes
                          Processor Information
                          	Socket Designation: CPU 6
                          	Type: Central Processor
                          	Family: Other
                          	Manufacturer: Intel
                          	ID: F1 06 04 00 FF FB CB 0F
                          	Version: Not Specified
                          	Voltage: Unknown
                          	External Clock: Unknown
                          	Max Speed: 2100 MHz
                          	Current Speed: 2100 MHz
                          	Status: Populated, Enabled
                          	Upgrade: Other
                          	L1 Cache Handle: Not Provided
                          	L2 Cache Handle: Not Provided
                          	L3 Cache Handle: Not Provided
                          	Serial Number: Not Specified
                          	Asset Tag: Not Specified
                          	Part Number: Not Specified
                          
                          Handle 0x0B00, DMI type 11, 5 bytes
                          OEM Strings
                          	String 1: Xen
                          	String 2: MS_VM_CERT/SHA1/bdbeb6e0a816d43fa6d3fe8aaef04c2bad9d3e3d
                          
                          Handle 0x1000, DMI type 16, 15 bytes
                          Physical Memory Array
                          	Location: Other
                          	Use: System Memory
                          	Error Correction Type: Multi-bit ECC
                          	Maximum Capacity: 24568 MB
                          	Error Information Handle: Not Provided
                          	Number Of Devices: 2
                          
                          Handle 0x1100, DMI type 17, 27 bytes
                          Memory Device
                          	Array Handle: 0x1000
                          	Error Information Handle: 0x0000
                          	Total Width: 64 bits
                          	Data Width: 64 bits
                          	Size: 16 GB
                          	Form Factor: DIMM
                          	Set: None
                          	Locator: DIMM 0
                          	Bank Locator: Not Specified
                          	Type: RAM
                          	Type Detail: None
                          	Speed: Unknown
                          	Manufacturer: Not Specified
                          	Serial Number: Not Specified
                          	Asset Tag: Not Specified
                          	Part Number: Not Specified
                          
                          Handle 0x1300, DMI type 19, 15 bytes
                          Memory Array Mapped Address
                          	Starting Address: 0x00000000000
                          	Ending Address: 0x003FFFFFFFF
                          	Range Size: 16 GB
                          	Physical Array Handle: 0x1000
                          	Partition Width: 1
                          
                          Handle 0x1400, DMI type 20, 19 bytes
                          Memory Device Mapped Address
                          	Starting Address: 0x00000000000
                          	Ending Address: 0x003FFFFFFFF
                          	Range Size: 16 GB
                          	Physical Device Handle: 0x1100
                          	Memory Array Mapped Address Handle: 0x1300
                          	Partition Row Position: 1
                          
                          Handle 0x1101, DMI type 17, 27 bytes
                          Memory Device
                          	Array Handle: 0x1000
                          	Error Information Handle: 0x0000
                          	Total Width: 64 bits
                          	Data Width: 64 bits
                          	Size: 8184 MB
                          	Form Factor: DIMM
                          	Set: None
                          	Locator: DIMM 1
                          	Bank Locator: Not Specified
                          	Type: RAM
                          	Type Detail: None
                          	Speed: Unknown
                          	Manufacturer: Not Specified
                          	Serial Number: Not Specified
                          	Asset Tag: Not Specified
                          	Part Number: Not Specified
                          
                          Handle 0x1301, DMI type 19, 15 bytes
                          Memory Array Mapped Address
                          	Starting Address: 0x00400000000
                          	Ending Address: 0x005FF7FFFFF
                          	Range Size: 8184 MB
                          	Physical Array Handle: 0x1000
                          	Partition Width: 1
                          
                          Handle 0x1401, DMI type 20, 19 bytes
                          Memory Device Mapped Address
                          	Starting Address: 0x00400000000
                          	Ending Address: 0x005FF7FFFFF
                          	Range Size: 8184 MB
                          	Physical Device Handle: 0x1101
                          	Memory Array Mapped Address Handle: 0x1301
                          	Partition Row Position: 1
                          
                          Handle 0x2000, DMI type 32, 11 bytes
                          System Boot Information
                          	Status: No errors detected
                          
                          Handle 0xFEFF, DMI type 127, 4 bytes
                          End Of Table
                          
                          
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                          • D Offline
                            deefdragon
                            last edited by

                            Out of curiosity, I dumped the DMI into a bin and opened it up in a hex editor.

                            I am seeing ASCII of the ID, but also a variant encoded in binary. In both cases, its formatted as 0b08f477-491a-a982-23c4-d224723624ea.

                            I believe the ASCII version is the one that gets populated into the serial number as it comes after ASCII encoded versions of the 3 lines above it in the decode.

                            TeddyAstieT 1 Reply Last reply Reply Quote 0
                            • TeddyAstieT Offline
                              TeddyAstie Vates 🪐 XCP-ng Team Xen Guru @deefdragon
                              last edited by TeddyAstie

                              @deefdragon said in VM UUID via dmidecode does not match VM ID in xen-orchestra:

                              Out of curiosity, I dumped the DMI into a bin and opened it up in a hex editor.

                              I am seeing ASCII of the ID, but also a variant encoded in binary. In both cases, its formatted as 0b08f477-491a-a982-23c4-d224723624ea.

                              I believe the ASCII version is the one that gets populated into the serial number as it comes after ASCII encoded versions of the 3 lines above it in the decode.

                              In SMBIOS 2.8, the UUID is supposed to be encoded in little endian (i.e Microsoft GUID). Yet it is put as big endian instead. So when Linux generates the UUID string from the SMBIOS table, it is considered as little endian which causes this mismatch.

                              SMBIOS 2.4 is supposed to be used (which appears to be using big endian UUIDs), but for some reason, something in XCP-ng UEFI supports forces it to be SMBIOS 2.8.

                              So the binary UUID is the same, just that it is interpreted with a different endianness due to accidental format change.

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