Public bug reported:
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 <r...@kernel.org> writes:
>> On 2024/07/11 06:20 AM, Rob Herring wrote:
>>> On Wed, Jul 3, 2024 at 8:17 AM Amit Machhiwal <amach...@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@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.
** Affects: linux (Ubuntu)
Importance: Medium
Status: Triaged
** Affects: linux (Ubuntu Noble)
Importance: Medium
Status: Triaged
** Affects: linux (Ubuntu Oracular)
Importance: Medium
Status: Triaged
** Also affects: linux (Ubuntu Noble)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Oracular)
Importance: Medium
Status: Triaged
** Changed in: linux (Ubuntu Noble)
Importance: Undecided => Medium
** Changed in: linux (Ubuntu Noble)
Status: New => Triaged
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https://bugs.launchpad.net/bugs/2074376
Title:
Disable PCI_DYNAMIC_OF_NODES in Ubuntu
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