BIOS partition copying should be skipped by ignition-ostree-transposefs on non-x86_64

[mikroskeem]

Describe the bug

https://github.com/coreos/fedora-coreos-config/blob/6e9f14e6f83ab13e58d81327d8c2d3e4f10d0bd3/overlay.d/05core/usr/lib/dracut/modules.d/40ignition-ostree/ignition-ostree-transposefs.sh#L288

When using boot_device.mirror.devices with Butane, it generates a configuration which is practically unusable on anything else but x86_64 - for example aarch64 does not ship with BIOS partition, it has only reserved partition with similar placement. I believe same issue is with PReP partition as well.

Reproduction steps

1. Use supplied Butane configuration snippet
2. Try installing FCOS via e.g. iPXE on non-x86_64 (e.g. aarch64)

Expected behaviour

Installation succeeds without attempting to copy existing BIOS partition (?)

Actual behaviour

Installation fails duringignition-ostree-transposefs with script attempting to copy non-existent partition.

System details

• Bare metal / QEMU
• Fedora CoreOS 40.20240920.3.0
• Butane v0.20.0 - v0.22.0

Butane or Ignition config

Butane snippet with `boot_device.mirror.devices`

---
variant: "fcos"
version: "1.5.0"

boot_device:
  mirror:
    devices:
      - "/dev/disk/by-path/pci-0000:02:00.0-nvme-1"
      - "/dev/disk/by-path/pci-0000:03:00.0-nvme-1"

Generated Ignition config snippet

{
  "storage": {
    "disks": [
      {
        "device": "/dev/disk/by-path/pci-0000:02:00.0-nvme-1",
        "partitions": [
          {
            "label": "bios-1",
            "sizeMiB": 1,
            "typeGuid": "21686148-6449-6E6F-744E-656564454649"
          },
          {
            "label": "esp-1",
            "sizeMiB": 127,
            "typeGuid": "C12A7328-F81F-11D2-BA4B-00A0C93EC93B"
          },
          {
            "label": "boot-1",
            "sizeMiB": 384
          },
          {
            "label": "root-1"
          }
        ],
        "wipeTable": true
      },
      {
        "device": "/dev/disk/by-path/pci-0000:03:00.0-nvme-1",
        "partitions": [
          {
            "label": "bios-2",
            "sizeMiB": 1,
            "typeGuid": "21686148-6449-6E6F-744E-656564454649"
          },
          {
            "label": "esp-2",
            "sizeMiB": 127,
            "typeGuid": "C12A7328-F81F-11D2-BA4B-00A0C93EC93B"
          },
          {
            "label": "boot-2",
            "sizeMiB": 384
          },
          {
            "label": "root-2"
          }
        ],
        "wipeTable": true
      }
    ],
    "raid": [
      {
        "devices": [
          "/dev/disk/by-partlabel/boot-1",
          "/dev/disk/by-partlabel/boot-2"
        ],
        "level": "raid1",
        "name": "md-boot",
        "options": [
          "--metadata=1.0"
        ]
      },
      {
        "devices": [
          "/dev/disk/by-partlabel/root-1",
          "/dev/disk/by-partlabel/root-2"
        ],
        "level": "raid1",
        "name": "md-root"
      }
    ]
  }
}

Additional information

I believe that it's easier to handle a workaround for this in ignition-ostree-transposefs than in Butane, as Butane is not aware about target system architecture currently.

[travier]

I moved this to the tracker. Please fill out the template from https://github.com/coreos/fedora-coreos-tracker/blob/main/.github/ISSUE_TEMPLATE/bug-report.yml

[jlebon]

You have to specify the layout to match your target architecture: https://coreos.github.io/butane/config-fcos-v1_5/.

Transferred this to the docs repo since I think the issue is more that we need to make this clearer in https://docs.fedoraproject.org/en-US/fedora-coreos/storage/.

[mikroskeem]

Did not notice boot_device.layout option. Indeed - it's bit unobvious and due to style in Butane page, not very convenient to see either.

Now knowing that this option exists, it solves my original issue.