missing scsi support/module in initramfs

[Ian Johnson]

With a hard disk VM that is using scsi, such as is the default on VMWare Fusion on macOS, the initramfs dies being unable to mount ubuntu-seed. See the attached screenshot for where it fails in the initramfs.

The same issue exists for uc16/uc18 and is reported here: https://bugs.launchpad.net/initramfs-tools/+bug/1894880 where the reported claims that the mptspi module must be inserted into the initrd to make it work. Perhaps the same module needs to be included in the initramfs to enable this for uc20 too.

[Dimitri John Ledkov (xnox)]

Can you boot a classic system and tell me the modules that are needed?

Is this for amd64 UC20 default build of the kernel.efi?

[Jerry Lee (jerry-lee-tpe)]

We saw the similar problem when UC-20 (AMD64) was tested on a commercial server.
With a testing kernel snap which specified to load that megaraid_sas module in the initramfs, this problem can be resolved.

Will the pc-kernel snap consider to include the megaraid_sas module ?

Thanks

Jerry

[Ian Johnson (anonymouse67)]

As to the original reason for this bug, on UC20 with the current pc-kernel, I had to add not just the mptspi kernel module but also it's dependencies, obviously. For brevity they were:

scsi/scsi_transport_spi.ko
message/fusion/mptbase.ko
message/fusion/mptscsih.ko
message/fusion/mptspi.ko

After adding all of these modules to the initramfs and then adding mptspi to modules-load.d/ubuntu-core-initramfs.conf also in the initramfs, then I was able to boot a UC20 VM using VMWare Fusion Player that was using all the default SCSI drive settings on my old Intel Macbook.

So it stands to reason if we want the generic amd64 pc-kernel to boot on as many VM software's out there as possible we should add these kernel modules to the initramfs or the kernel itself. It appears that these modules add a total of 281K (uncompressed) to the initramfs, so IMHO they are intrusive to add.

[Dimitri John Ledkov (xnox)]

core-initrd v40 has "main" and "server" features. And both features are enabled by default for the amd64 builds.

the 67 abi kernel snap should contain relevant modules.