VIO bus not initialized

[Michael Ellerman]

Paul Menzel <pmenzel at molgen.mpg.de> writes:
> Dear Linux folks,
>
>
> On the POWER8 system IBM S822LC, Linux 5.12-rc2+ logs the errors below.

That's a bare metal system, you can see that from the line "Using
PowerNV machine description" in the boot log.

>      $ dmesg --level=err
>      [    1.555668] Driver 'hvc_console' was unable to register with 
> bus_type 'vio' because the bus was not initialized.
>      [    1.558434] Driver 'tpm_ibmvtpm' was unable to register with 
> bus_type 'vio' because the bus was not initialized.
>      $ grep VIO /boot/config-5.12.0-rc2+
>      CONFIG_IBMVIO=y

The "vio" bus is not a real bus, it's a fake bus we use for hypervisor
provided devices in LPARs (guests).

So on bare metal machines there is no vio bus, the devices that would
appear on the vio bus are found via other mechanisms.

> [    1.555668] Driver 'hvc_console' was unable to register with bus_type 'vio' because the bus was not initialized.
> [    1.555866] hvc0: raw protocol on /ibm,opal/consoles/serial at 0 (boot console)
> [    1.555875] hvc0: No interrupts property, using OPAL event

You can see here that the hvc opal driver found the console, which is
the bare metal equivalent of the hvc console (vio) driver.

> [    1.556205] Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled
> [    1.558377] Non-volatile memory driver v1.3
> [    1.558404] Linux agpgart interface v0.103
> [    1.558434] Driver 'tpm_ibmvtpm' was unable to register with bus_type 'vio' because the bus was not initialized.

The ibmvtpm driver is a Virtual TPM driver, so it also isn't present on
a bare metal system.

I don't think that system has a TPM, but if it did you'd need the
appropriate bare metal TPM driver to use it.

cheers