Re: [PATCH] kunit: Enable PCI on UML without triggering WARN()

[Johannes Berg <johannes@sipsolutions.net>]

On Fri, 2025-06-27 at 17:21 +0200, Thomas Weißschuh wrote:
> Various KUnit tests require PCI infrastructure to work.
> All normal platforms enable PCI by default, but UML does not.
> Enabling PCI from .kunitconfig files is problematic as it would not be
> portable. So in commit 6fc3a8636a7b ("kunit: tool: Enable virtio/PCI by default on UML")
> PCI was enabled by way of CONFIG_UML_PCI_OVER_VIRTIO=y.
> However CONFIG_UML_PCI_OVER_VIRTIO requires additional configuration of
> CONFIG_UML_PCI_OVER_VIRTIO_DEVICE_ID or will otherwise trigger a WARN() in
> virtio_pcidev_init(). However there is no one correct value for
> UML_PCI_OVER_VIRTIO_DEVICE_ID which could be used by default.
> 
> This warning is confusing when debugging test failures.
> 
> On the other hand, the functionality of CONFIG_UML_PCI_OVER_VIRTIO is not
> used at all, given that it is completely non-functional as indicated by
> the WARN() in question. Instead it is only used as a way to enable
> CONFIG_UML_PCI which itself is not directly configurable.
> 
> Instead of going through CONFIG_UML_PCI_OVER_VIRTIO, introduce a custom
> configuration option which enables CONFIG_UML_PCI without triggering
> warnings or building dead code.

Alright, so looked like Thomas wanted this to not be merged via the UML
tree, which does make sense, so I've dropped it.

For the kunit tree then you can add:

Reviewed-by: Johannes Berg <johannes@sipsolutions.net>

johannes