virtio disk not supported

[hadmut]

Describe the bug

Hi,
I am not really sure whether this is a bug or an intentional company decision.

Today I read a recommendation to use Photon OS, wanted to try it, and found, that it is not possible to install it in a virtual machine: It just does not find the disk device /dev/vda to install on.

The reason is, that

/usr/lib/python3.11/site-packages/photon_installer/device.py

calls lsblk to look for disks with option '-I', '7,8,179,202,254,259', which keeps /dev/vda (major 253) out of the list.

I wonder if this is intentionally restricted to vmware environments, has technical reasons, or is just an unintentional omission.

regards

Reproduction steps

1. run the iso installer image in kvm/qemu with virtual disk, if=virtio
2. try to install it
3. notice that photon-installer fails and aborts because no disk can be found.
   ...

Expected behavior

Installation

Additional context

No response

[dcasota]

Hi,
the virtual hardware of the boot media must be sata. See vmware/photon#1393

[oliverkurth]

Thanks for reporting! This is most likely an oversight, I don't think we intentionally exclude KVM. I can give it a try by adding 253 to the list. I am not familiar with KVM though.

@dcasota IIUC, this is about finding the hard disk to install to, not the CD device to install from.

[YustasSwamp]

Hi @hadmut , thanks for raising this.
/dev/vda device driver uses dynamic major number allocation. It can be anything in the range [240-254] as mentioned here https://www.kernel.org/doc/Documentation/admin-guide/devices.txt
Seems like in your case 254 is already occupied by some other device.
I remember we already added 254 for the same reasons (for vda support), probably it makes sense to include entire range or at least last N elements.
And we are always open for external contributions))

[YustasSwamp]

@oliverkurth we should be less restrictive in block device discovery mask.

[YustasSwamp]

Let's remove a mask ("-I 7,8,179,202,254,259") and allow user to pick any disk.

[hadmut]

@dcasota: Good hint. Providing the disk as sata makes the installation run.

Unfortunately, just calling qemu/kvm and omitting the if= parameter doesn't make the disk a sata disk. It takes the parameter -M q35 to emulate a particular hardware model, which makes my machine complain about a missing CPU feature, but runs. Nevertheless, virtio should be supported.

[oliverkurth]

I have it fixed locally. I will push the fix soon, and give some instructions how to use it.

[oliverkurth]

I have created a PR with a fix, and instructions on building your own ISO: #24