Re: [Qemu-devel] [PATCH 42/52] i386: express dependencies with Kconfig

[Paolo Bonzini]

On 14/02/19 17:54, Michael S. Tsirkin wrote:
> On Thu, Feb 14, 2019 at 05:47:08PM +0100, Paolo Bonzini wrote:
>> On 01/02/19 16:05, Philippe Mathieu-Daudé wrote:
>>> This lacks a DISPLAY dependency?
>>>
>>> $ i386-softmmu/qemu-system-i386 -M q35
>>> qemu-system-i386: Unknown device 'VGA' for bus 'PCIE'
>>> Aborted (core dumped)
>>
>> If you got this with --without-default-devices, then it's intended behavior.
>>
>> VGA_PCI is selected via CONFIG_PCI_DEVICES.
> 
> OK but I guess as a follow-up patch we can hide things that don't work,
> or select things that are required?

It is not required; if you use "-nodefaults" you can build without
CONFIG_VGA_PCI (the failure mode is horrible, granted; it's the same
today if you modify pci.mak).  The documentation explains this for
--without-default-devices:

  When QEMU is built with this option, the user will probably
  want to change some lines in the first group, for example like this::

    CONFIG_PCI_DEVICES=y
    #CONFIG_TEST_DEVICES=n

  and/or pick a subset of the devices in those device groups.

Paolo