Re: [PATCH v8] PCI: hotplug: Add a generic RAS tracepoint for hotplug event

[Lukas Wunner <lukas@wunner.de>]

On Tue, May 20, 2025 at 01:07:28PM +0300, Ilpo Järvinen wrote:
> On Tue, 20 May 2025, Shuai Xue wrote:
> > , and the format of "Link Speed changed" is a bit different from 
> > "pci_hp_event".
> 
> The difference is only because when the Link is down, there's no Link
> Speed (obviously). Whenever a new device is hotplugged and it comes up, 
> there's also Link Speed for it which can be included into the trace event. 
> 
> I think the trace event should have some special value for the fields that 
> are N/A due to Link being off. While it would be possible to create 
> separate events for speed changes and hotplug, I don't see any pros in 
> that approach over just having the N/A fields marked as such when the Link 
> is Down.

Link speed changes and device plug/unplug events are orthogonal,
I don't think they should be mixed together in the same event.

A link speed event can be signaled simultaneously to a plug event
and then user space can decide in which type of event it's
interested in.

That also avoids the awkwardness of having N/A values for the
link speed on unplug.

Thanks,

Lukas