When creating a snapshot, why can't I select VM-generation and VM architeture? Fields are greyed out

Question

I am planning to test the ARM64 architecture in Azure with a DPDK based firewall. I would like to understand how I can troubleshoot this problem I have - or if the issue comes from Azure not having offered ARM64 support before and somehow now there is a dependency problem here that does not allow the user to make a certain selection?

It is a fairly simple test. I have mounted an additional disk to a Linux based VM and used 'dd' software on Linux host to perform a disk dump of a DPDK based ARMv8-A firewall image to a disk. This method worked fine using x64 based systems to import a VM. Subsequently next step in this process is to create a snapshot from this disk image - and finally I convert the snapshot to an image that can be used to launch a VM.

Where I struggle is in the snapshot creation step, when I select my disk image and click on 'Create snapshot'

VM generation that I need to set to gen 2 because ARM64 uses UEFI, and also architecture that I must change to ARM64 is greyed out and set to x64?

Would there be any way I can troubleshoot this why the fields are greyed out, or am I doing something wrong? Or can this be a case of something they forgot to implement in the snapshot creation when introducing ARM64?

Thanks.

Answer 1

Hi @Kimmo

It's actually just information and not an option to be selected.
In this case, the disk you are taking the snapshot on is generation 1

Just like:
]1

Get in touch if you need more help with this issue.

--please don't forget to "[Accept the answer]" if the reply is helpful--

Answer 2

@Kimmo Thanks for reaching out to Microsoft Q&A. Just adding to the above answer...

As mentioned above, when creating a snapshot, you do not have the choice to select the generation and architecture. This is an option when creating a VM itself as shown below-

Hope this helps. If you have any further questions, please do let us know and we will be glad to assist further. Thank you!
Remember:

Please accept an answer if correct. Original posters help the community find answers faster by identifying the correct answer. Here is how.

Want a reminder to come back and check responses? Here is how to subscribe to a notification.

Answer 3

Thanks.

Got it - no architecture nor generation settings in snapshots, this has been helpful.

This leads me into my next challenge.

What I have done is to perform a disk dump of an ARM64 based DPDK firewall image to an unmanaged disk. I want to turn this disk into a VM.

To do this, I use the following method:

If we go back to when I did this for x64 based arch VMs, I used this method successfully to create a snapshot from the disk, and the snapshot is in the next step converted to an Image - and from the Image I can build the VM. This works well with x64 but I cannot use the same method with ARM64 because I have not found a way to insert an architecture parameter.

To do this, I use this guide + PowerShell (this section: Create a managed image from a snapshot using PowerShell) - https://learn.microsoft.com/en-us/azure/virtual-machines/windows/capture-image-resource

What I have is (I modified New-AzImageConfig to add gen 2 parameter) :

$rgName = "Diskwriter_group"  
$location = "NorthEurope"  
$snapshotName = "vendor-ARM"  
$imageName = "vendorARM"  
  
$snapshot = Get-AzSnapshot -ResourceGroupName $rgName -SnapshotName $snapshotName  
  
$imageConfig = New-AzImageConfig -Location $location -HypervGeneration V2  
$imageConfig = Set-AzImageOsDisk -Image $imageConfig -OsState Generalized -OsType Linux -SnapshotId $snapshot.Id  
  
New-AzImage -ImageName $imageName -ResourceGroupName $rgName -Image $imageConfig  

Here I assume the I must somehow add a parameter to change architecture from x64 to ARM64 somewhere - or to do this with some other method? When I run this, I get an image that is gen2 - and this is shown upon completion.

ResourceGroupName : Diskwriter_group
SourceVirtualMachine :
StorageProfile : Microsoft.Azure.Management.Compute.Models.ImageStorageProfile
ProvisioningState : Succeeded
HyperVGeneration : V2
Id : /subscriptions/x/resourceGroups/Diskwriter_group/providers/Microsoft.Compute/images/vendorARM
Name : vendorARM
Type : Microsoft.Compute/images
Location : northeurope
ExtendedLocation :
Tags : {}

Subsequently, using this image results in ARM64 being greyed out upon VM creation since ARM64 is not set on the image when I do this

Questions based on this:

Is there any way to do this image creation with PowerShell where architecture can be specified when building the image - I see no architecture option in New-AzImageConfig that I use https://learn.microsoft.com/en-us/powershell/module/az.compute/new-azimageconfig?view=azps-8.3.0?

Maybe there is a better / different way to achieve the same result (custom VM with ARM64 arch set combined with Gen2) from a Linux based image?

Thanks!