doesn't detect the subarchitecture xgene-uboot for a HP m400 cartridge

I wasn't able to deploy this system, it got stuck on a PXE boot loop "bug 1918977".
Manually changing its architecture configuration to `arm64/xgene-uboot` - I can successfully deploy this cartridge with Ubuntu Trusty, Xenial and Bionic.

There's the appropriate mapping of this subarch
"ProLiant m400 Server Cartridge": "arm64/xgene-uboot" on MAAS code.
I wonder if it got broken at some point.

What's the output from `show node info <node-id>` on that chassis?

hpiLO->show node info c34n1

  c34: #Cartridge 34
    Type: Compute
    Manufacturer: HP
    Product Name: ProLiant m400 Server Cartridge
    Product ID: 721717-B21
    AutoRev: 0A
    Serial Number: CN7505VJ55
    Power: Off
    c34n1: #Node 1
      Node Asset Tag:
      DIMM 1:
        DIMM Capacity: 8 GB
        DIMM Serial Number: 00000000
      DIMM 2:
        DIMM Capacity: 8 GB
        DIMM Serial Number: 00000000
      DIMM 3:
        DIMM Capacity: 8 GB
        DIMM Serial Number: 00000000
      DIMM 4:
        DIMM Capacity: 8 GB
        DIMM Serial Number: 00000000
      DIMM 5:
        DIMM Capacity: 8 GB
        DIMM Serial Number: 00000000
      DIMM 6:
        DIMM Capacity: 8 GB
        DIMM Serial Number: 00000000
      DIMM 7:
        DIMM Capacity: 8 GB
        DIMM Serial Number: 00000000
      DIMM 8:
        DIMM Capacity: 8 GB
        DIMM Serial Number: 00000000
      NIC 1 MAC Address: 14:58:d0:58:93:92
      NIC 2 MAC Address: 14:58:d0:58:93:93
      HDD 1: # Disk 1
        Firmware: HPS4
        Model: XR0240GEBLU
        Serial Number: 14200EEFA453
        Wear: 0%

hpiLO->

Could you provide logs from commissioning that result in an attempt to deploy arm64/generic subarch?

[Expired for MAAS because there has been no activity for 60 days.]

I've attached the output of the 50-maas-01-commissioning script. I'm not sure if that is what you are looking for - if not, can you be specific on how to collect the needed logs?

During recommissioning, MAAS currently always resets the subarch to generic. We could change this to preserve it, since we only get the arch (not the subarch) from commissioning data.