On 7/13/2016 4:09 PM, Alex Williamson wrote:

quoted

et me explain the rationale.

quoted

As you know, there can be two kernel build combinations. One build where 
ACPI is not selected in Kconfig and another one with the ACPI Kconfig.

In the first case, CONFIG_ACPI is stubbed out in this file and DT user
will not see any kind of messages from ACPI. 

In the second case, both DT and ACPI is compiled in but the system is booting with
any of these combinations. 

If the firmware is DT type, then acpi_disabled is 1. The ACPI probe routine
terminates immediately without any messages. 

If the firmware is ACPI type, then acpi_disabled is 0. All other checks are valid
checks. We cannot claim that this system is DT.

Thanks, this sort of information and assumption should be documented in
a comment since not all of us care whether a DT device can appear in an
ACPI config or not.  Also note that acpi_disabled and ACPI_COMPANION
are defined regardless of CONFIG_ACPI, so really we only need to wrap
acpi_device_hid() in an #ifdef, we could skip the separate stub.
Thanks,

Sure, I'll add the sentences above as a comment to top of the probe function.

I also got rid of stub vfio_platform_acpi_probe function and moved CONFIG_ACPI
inside the vfio_platform_acpi_probe function as you suggested.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.