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

[Roxana Nicolescu]

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(-)

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2.34.1