[BUG]: 'hv_balloon' driver fails to load AlmaLinux OS 8 AArch64 Azure images

[jaboutboul]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

Details:

location: northeurope

Expectation: All HyperV Drivers to be loaded successfully

Observation: We notice that the 'hv_balloon' driver fails to load and an error as such is thrown on Alma8 alone:

AssertionError: [Not all Hyper V drivers are present.] Expected <['hv_balloon']> to be of length <0>, but was <1>.

Environment Details:

VM Size: Standard_D64pds_v6 (Any SKU Size)

Images: almaLinux almalinux-arm 9-arm-gen2 latest

It looks like the hv_balloon driver is disabled from the kernel config.

CONFIG_HYPERV_BALLOON is not set

Can we fix this?

Expected Behavior

the hv_balloon driver to be loaded properly.

Steps To Reproduce

No response

Anything else?

No response

Search terms

hv_balloon, azure

[LKHN]

Jack, Thanks for reporting!

Looks like this issue is related on the AArch64 architecture since SKU of an ARM64 VM is mentioned as Standard_D64pds_v6.

I just tried to reproduce the issue on images with URNs below:

• almalinux:almalinux-arm:8-arm-gen2:8.10.2024082001
• almalinux:almalinux-arm:9-arm-gen2:9.5.202411260
• almalinux:almalinux-arm:9-arm-64k-gen2:9.5.202411260
• almalinux:kitten:10-arm64-gen2:10.20241226.0

I can confirm that I am able to reproduce issue only on AlmaLinux OS 8:

• almalinux:almalinux-arm:8-arm-gen2:8.10.2024082001

# lsmod | grep -Ei 'hv_balloon'
# echo $?
1

Due to how the kernel is built, rather than the Azure cloud image build process, I believe this is outside the scope of the Cloud SIG.