APPLIED[N]: [SRU][N/O/U][PATCH 0/1] Disable PCI_DYNAMIC_OF_NODES

[Roxana Nicolescu]

On 01/08/2024 16:54, Roxana Nicolescu wrote:
> BugLink: https://bugs.launchpad.net/bugs/2074376
>
> This came in via KTML from upstream. It is part of a discussion between
> upstream and IBM reporting a bug which occurs in KVM:
>
> Rob Herring <robh at kernel.org> writes:
>
>>> On 2024/07/11 06:20 AM, Rob Herring wrote:
>>>> On Wed, Jul 3, 2024 at 8:17 AM Amit Machhiwal <amachhiw at linux.ibm.com> wrote:
>>>>> With CONFIG_PCI_DYNAMIC_OF_NODES [1], a hot-plug and hot-unplug sequence
>>>>> of a PCI device attached to a PCI-bridge causes following kernel Oops on
>>>>> a pseries KVM guest:
>>>> Can I ask why you have this option on in the first place? Do you have
>>>> a use for it or it's just a case of distros turn on every kconfig
>>>> option.
>>> Yes, this option is turned on in Ubuntu's distro kernel config where the issue
>>> was originally reported, while Fedora is keeping this turned off.
>>>
>>> root at ubuntu:~# cat /boot/config-6.8.0-38-generic | grep PCI_DYN
>>> CONFIG_PCI_DYNAMIC_OF_NODES=y
>> Ubuntu should turn off this option. For starters, it is not complete
>> to be usable. Eventually, it should get removed in favor of some TBD
>> runtime option.
>>
>> (And we should fix the crash too)
> This option is described in the config system as:
>
>    This option enables support for generating device tree nodes for some
>    PCI devices. Thus, the driver of this kind can load and overlay
>    flattened device tree for its downstream devices.
>    .
>    Once this option is selected, the device tree nodes will be generated
>    for all PCI bridges.
>
> Open Firmware (OF) would be used for KVM for UEFI mode. The reported bug
> was related to hot-unplugging PCI devices. My guess would be that this
> probably is not of much use to the majority of users and might even go
> away. So it should really be disabled in Ubuntu, too.
>
> Roxana Nicolescu (1):
>    UBUNTU: [Config] Disable PCI_DYNAMIC_OF_NODES
>
>   debian.master/config/annotations | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
Applied to noble:linux master-next branch. Thanks!