gcp: set CONFIG_IDPF=y for Intel Infrastructure Data Path Function Driver

[Matthew Ruffell]

BugLink: https://bugs.launchpad.net/bugs/2066320

[Impact]

GCE C3 Metal instance type requires the Intel IDPF driver for networking to function.

On the Mantic kernel, this was built into the kernel:

# grep IDPF /boot/config-6.5.0-1020-gcp
CONFIG_IDPF=y

On Noble, this is now been included as a module, in modules-extra:

# grep IDPF /boot/config-6.8.0-1007-gcp
CONFIG_IDPF=m

# dpkg -S /lib/modules/6.8.0-1007-gcp/kernel/drivers/net/ethernet/intel/idpf/idpf.ko.zst
linux-modules-extra-6.8.0-1007-gcp: /lib/modules/6.8.0-1007-gcp/kernel/drivers/net/ethernet/intel/idpf/idpf.ko.zst

modules-extra is not included in GCP cloud images, and thus, C3 Metal instance types have no networking. They cannot install modules-extra either.

[Fix]

Set CONFIG_IDPF=y for GCP kernels.

Leave -generic as CONFIG_IDPF=m for all architectures.

[Testcase]

$ grep -Rin "IDPF" /boot/config-$(uname -r)
CONFIG_IDPF=m

Check /lib/modules/$(uname -r)/kernel/drivers/net/ethernet/intel/idpf/idpf.ko

A test package is available in the following ppa:

https://launchpad.net/~mruffell/+archive/ubuntu/sf385823-test

If you install it, the IDPF driver will be available in the kernel image, instead of the module being built.

e.g.

$ grep -Rin "IDPF" /boot/config-$(uname -r)
CONFIG_IDPF=y

[Where problems could occur]

We are building the IDPF driver into the kernel image. This will slightly increase the kernel size by a negligible amount.